Titus Lucretius Carus ([99?] 95 - [55?] 50 BC) was an excellent Epicurean philosopher and poet in which very little is known of his life, however, this poem which is best translated to be called " On the Nature of Things", is his best work that sheds light on his character and view of the nature of the universe. He ends up being one of the earliest substantial representatives of Atomism which was supported and argued for by quite a few early philosophers such as Leucippus and Democritus a few centuries before Lucretius. Atomism generally is belief in the nature of substances being made up of and voids and generally implied a mechanistic view of nature. Atomism ultimately was debated, discussed, and supported to great lengths from Leucippus to Democritus to Newton to Dalton to Bohr. The views of Atoms we have today in Physics and Chemistry are a legacy of these and earlier Atomists. As such theories of atoms are ridiculously old and are not "modern" at all. They are ancient just as Heliocentrism, Geometry, Trigonometry, Statics, Kinematics, Vacuums, Plastic surgery, Zoology, Anatomy, Optics, Medicine, Megnetism, Material sciences, and lots of other disciplines and theories that are not new at all. Please read some primary documents on the historical sciences The Mathematics of Egypt, Mesopotamia, China, India, and Islam: A Sourcebook and Greek Science of the Hellenistic Era: A Sourcebook. For a basic history of the philosophy of the atom before the modern atomic age please read Atomism and Its Critics: From Democritus to Newton. By the way, the word "atom" is from the Greek word "atomos" which literally means "uncut or undissectable". For those interested in Democritus and other pre-Lucretius and pre-Epicurean atomistic views from available fragments please read Handbook of Greek Philosophy: From Thales to the Stoics: Analysis and Fragments and Early Greek Philosophy (Penguin Classics).
Lucretius serves to be an excellent poet who reflects some views on nature that existed during his time. Many people who read this book may get a weird sense that atomism leads to metaphysical naturalism (one of the denominations of atheism) , however, it should be noted that though Lucretius mentions and criticizes "religion" as a "crushing burden on human life" that poisons life, it must be noted that Lucretius' arguments against "religion" are not arguments against the existence of gods or even all forms of religion necessarily since he seems to focus on how some perceive causes for natural phenomenon. Critical editions of Lucretius like the Loeb Classical Library has a more accurate translation than Oxford World's Classics and includes the Latin parallel texts.
In the footnotes from the Loeb Classical Library Latin-English edition it is clear that the words translated as "religion", in this Oxford World's Classics, such as "religio", that Lucretius was really talking about superstition and false religion rather than "religion" itself since Epicureans did not deny religion. Epicureans like Lucretius also did not deny the existence of gods necessarily either, they simply denied that gods interacted with humanity and the world. Book 6.68-79 shows how he was not opposed to true religion. Generally his arguments are against those who appeal to the supernatural as holistic explanations of phenomena in nature. His atomistic views help him explain the universe from a purely naturalistic perspective where the universe is autonomous, self sustainable, and infinite without direct intervention by gods. This view is similar to Pliny the Elder's view of nature even though Pliny seems to incline towards beliefs in gods every once in a while. Pliny was an ancient who wrote a work called "Natural History" and gives insight to ancient natural philosophy (science) and was used widely by medieval scientists like numerous Christians. For those interested in Epicurean philosophy, his writings, and fragments, from which Lucretius generally builds on, please read The Essential Epicurus: Letters, Principal Doctrines, Vatican Sayings, and Fragments (Great Books in Philosophy). It is interesting to note, that Epicurus, who inspired part of Lucretius' views, did believe in the existence of the gods and an infinite universe, but did not like it when people used an exclusive supernatural explanation, when normal reasons could be given to elucidate a physical event too.
Here are some things that he mentions in his work and believes (there is more he mentions than what I mention):
Atoms are primal elements of things; he believes religion is "a crushing burden" on human life; he believes religion has resulted in "criminal" deeds - one example is provided; things come into being without the aid of the gods; nothing comes from nothing; nature resolves everything to their elements, never to nothing; multiple examples of different combinations of atoms in nature are provided; all things are porous with bodies and void - example things with same volume have different masses; collision of 2 moving bodies ; all nature consists of 2 things: elementary bodies and voids that are both independent and unmixed with each other; where there is matter there is no void and vice versa; erroneous philosophies such as of those who think the universe consists of fire alone or Anaxagoras' "Homeomeria" where wholes are made up of homogeneous identical parts (example: earth is made up of little earths and flesh is made up of little fleshes) are addressed; the universe has no boundaries; atoms did not get placed to form order by design, but instead were placed by multiple random interactions for ages; objections are raised to the theory that all things head to the center of the earth
Movements and causes of movements of atoms; he thinks men err in assuming gods ordered all things for the sake of mankind; another cause of motion of atoms is free will; atoms have different shapes and textures and the varieties are finite, however the numbers of atoms is infinite; atoms have no color, smell, sound, moisture, heat or feelings; explanation for the existence of the senses in creatures which are all made of atoms; death disperses atoms and then they reunite; the universe has many other worlds and they are all made by atoms not by gods
Mind and spirit are discussed; the mind is made of atoms; some stuff on the senses; mind and spirit are finite mortal substances; if mind and spirit split form the body the person is dead; spirit is divided throughout the body; multiple problems emerge for those who believe the mind to be immortal (examples of problems are given); a case against reincarnation and why it is absurd; death is ultimately nothing to be feared
Discourse on mirrors and images; how images travel; how sight functions; our eyes don't like bright objects; why we can see dark things; the concept of truth comes from the senses; the senses cannot be refuted; all 5 senses cannot refute other senses since their domains are separate in type and quality of what they sense; the nature and explanation of sounds; nature of smells and taste are discussed; memory faints in sleep; sleep and our spirits; on dreams; male sexual arousal; on women; love and romance; avoiding love; how women behave with men; gods, by their will or decree, are not the ones preventing men from producing offspring, it's men's sperm or "seed" that prevents men from reproducing; what women at that time did to prevent themselves from getting pregnant
Attempts to explain the creation of the world to creation of creatures to the fear of gods in man; you cannot believe the dwelling of the gods to be in this world; not much can be said of the nature of the gods since they are beyond our senses; how would the gods have come up with a plan for creation?; earth and air are finite; objections raised to those who believe in the immortality of the earth and the interpretation that the gods have made an infinite creation; Democritus' opinion on the traveling of heavenly bodies; the light of the moon is from the sun's rays or the it has it's own light; phases of the moon; animals are created from earth (earth is the matter of all creatures); extinctions of creatures; creatures of double natures like Centaurs could never have existed; primitive man to men of language; fire came to man by lightning; where reverence for the gods emerged among nations; comments on worship of gods and people's beliefs in the overseeing governance of the gods; how metals were first found; usage and value of metals; usage of animals in battles; one universe many worlds; from painted garments to cloth - how women got the job; the world was not made by the gods, but by atoms; development of man to civilization
All realms of the universe are mortal (heavens, earth); ignorance of some who are educated about the gods; explaining lightning and thunderstorms; reason for not believing that Jupiter and the gods are directing thunderbolts - they never aim at criminals or guilty people who deserve to get bolted along with other reasons; causes of earthquakes - 2 cases: Sidon in Syria and Aegeum in Palponnese; many things have purely natural origins, not supernatural origins; the gods are not below the earth; atoms manifest in multiple fashions; discourse on the nature of magnets; the term "Magnet" was named by the Greeks who found these in Magnete's land; structure of objects are most porous; how magnets attract is explained via atomic reasons; nature of diseases, plagues, and pestilence are discussed; death by disease and grief
****To those who wish to read Lucretius in Latin in a critical edition please read:
"Lucretius: On the Nature of Things (Loeb Classical Library No. 181 Bks. 1-6)"
Overall, Lucretius is a great read for those interested in the history of "science" and "religion" and how ancient naturalistic views held up with other competing explanations or mixtures of explanations on natural phenomenon. Lucretius' work demonstrates the diversity of interpretations of nature that existed at the time. This diversity still exists today. Those who read Lucretius will notice that some of Lucretius' ideas seem to be ahead of his time. However, I am not sure if his ideas were modern or if our ideas, in our modern age, are really old and ancient. The ancients don't seem to be that far off from the truth concerning their understanding of nature.
Since the inferences of "religion" and "science" are found throughout this edition by Oxford World's Classics, it is recommended that readers investigate the complex and complementary history of both "religion" and "science". Historically, the atomistic view has been championed by many theists, most notably Muslims and Christians. Newton, Leibniz, Bacon, and Boyle, for example, ended up developing a mechanistic worldview with their theism which is very much how many people in the past believed. Atheists have done the same with their atheism though historically atheistic contributions to science have been far less than the quantity of contributions theists have hauled in terms of foundational research, generation of fields of science, and furthering inquiries on nature except in perhaps the past century and a half. For research on the relationship between the sciences and religions of theism please read Science and Religion: A Historical Introduction and 1001 Inventions: Muslim Heritage in Our World and also the primary sources by theist scientists themselves. For research on the relationship between the sciences and the religion of naturalistic atheism please read Science and Nonbelief and primary sources by atheist scientists.
Some who read Lucretius may think, via historical ignorance and stereotype, that the sciences are implicitly atheistic, in that they support an atheistic world view, but it must be remembered that the sciences are theistically and atheistically neutral in the same way that the sciences are politically, sexually, and racially neutral. Science is universal and secular. The study of nature has been done by both theists like Hippocrates to Bacon to Maxwell to Planck and atheists from Russell to Pauling to Thorne to Weinberg. Theists and Atheists live in the same universe, and neither rejects nature since they use it all the time inevitably. Theists simply add more stuff to their naturalism when discussing theological matters. It is absurd to believe, as some laymen and even many historically ignorant modern scientists do, that theists have done very little in the studies of nature and that they use the supernatural to justify everything. This is absurd since reading primary sources by theistic scientists from ancient to modern sources, one rarely encounters citations of scripture or tradition. Interestingly, it was theistic societies that developed modern science, not atheistic societies like much of Asia even though they had many opportunities Intellectual Curiosity and the Scientific Revolution: A Global Perspective. Historically naturalist atheist scientists have been rare until the past century and a half. Theist scientists have generated fields of science and have done most significant contributions to science through time such as Pythagoras, Euclid, Ptolemy, Aristotle, Hippocrates, Galen, Ockham, Roger Bacon, Francis Bacon, Newton, Leibniz, Boyle, Faraday, Maxwell, Planck, Galileo, Pascal, Mendel, Euler, the Bernoulli family (i.e. Johann, Daniel, etc), Dalton, Kepler, Linnaeus, Joule, Stokes, Kelvin, Lavoisier, Pasteur, Ampere, Volta, Copernicus, Van der Waals, Ibn Sina, Einstein (Spinoza's god), Heisenberg, Hooke, Bayes, Malthus, Gauss, Riemann, Mendeleev, Hutton, Watt, Lamarck, Boltzmann, and many other giants. They laid much of the groundwork for science today which everyone today has built on top of.
A good list can be found in "Scientists of Faith: 48 Biographies of Historic Scientists and Their Christian Faith" and others can be found in previously cited references.
Annie Laurie Gaylor, Co-President of Freedom From Religion Foundation, which is a religious atheist sect that strongly resembles Christian organizations, actually struggled in her essay in "Parenting Beyond Belief: On Raising Ethical, Caring Kids Without Religion" to actually name notable atheist and agnostic scientists. She could only name a small handful and she included theists in her list too, which actually reduces the amount of scientific giants that are atheists or agnostics. It seems agnostics and atheists have made their bulk of contributions in metaphysical philosophy or politics, but not so much in science. Finally in this last century you find atheists being more involved and interested in science than previous generations. Don't take my word for it research for yourselves.
For a good summary of when modern atheism spawned (17th century, not before), and the relationship it had with science up to this century one can see Oxford and Cambridge's review from the "Investigating Atheism" project under the "Atheism & Science" section online for free.
*** Scientific discovery and technological progress can be seen in every age from the ancient, medieval, and pre-modern periods. See, for example, the advancements on studies in nature from the Middle Ages, which pseudo historians and historically ignorant people incorrectly call the "Dark Ages", from actual readings from Medieval scientists themselves in their own words in :
"A Sourcebook in Medieval Science (Source Books in the History of the Sciences)" - Edited by Edward Grant.
"Cathedral, Forge and Waterwheel: Technology and Invention in the Middle Ages" - Joseph Gies is about technological advancements.
In the early and late middle ages, monks were known to be very much involved in scientific research among other things.