This luminous book is a real introduction to the "indirect" method of painting: the use of translucent layers to build the glow seen in both Fra Angelico's pure tempera and Rembrandt's oils.
Many beginning artists have a "mental model" of painting *alla prima* on a white primed canvas, but this method only dates to the Impressionists. By the 1840s, the older method, of starting out in monochrome with warm pigments and a middle toned ground, had produced a by-then wearisome academic look known as the "brown soup".
But before the brown soup of Sir Joshua Reynolds, the tempera painters of the Middle Ages started out, in somewhat the same way as the Impressionists, on a brilliant white surface, gesso on wood.
Thompson shows the student how to use the considerable amount of reflected light from this ground by painting not opaquely ("we are not doing gouache!"), nor transparently like Titian and Veronese, but translucently, obscuring and refining form in thin layers of pure pigment.
Amazingly, in egg tempera, you can get brilliant yellows using only "yellow ochre", an earth tint, for yellow. This is because each color, properly applied in this fast-drying media, works with the white of the ground to produce restrained, yet brilliant effects.
Don't look at Andrew Wyeth for these effects: although a brilliant artist in egg tempera, Wyeth was uninterested in color apart from the tertiary. Look instead upon Fra Angelico, and for even more brilliant effects, examine how Jan van Eyck combined the slightly paler color of tempera with oil glazes.
Of course, you may not have access to the raw materials Thompson specifies. Unless you are a carpenter, it may be hard to find, evaluate and reinforce the wood panels required for classic tempera (canvas is too flexible for tempera). You also need powder colors, powder gesso, and "rabbit skin glue".
The powder colors, as another poster points out, may be hazardous, and many vegetarian and vegan artists today may not want their paintings to include the glue produced by bunny rabbits.
However, if you learn the classic method from Thompson, being careful to not use hazardous colors and using synthetic glue, you can use the approach in acrylics on canvas. Acrylics when sufficiently diluted and when applied with sable and round bristle brushes as is classic egg tempera, can create effects similar to those of tempera, and then can be glazed to produce 16th century Flemish effects.
Having learned from Thompson, I save a lot of money, since the only colors I need to make a painting are Mars black and titanium white for the underlying *grisaille*, and black, white, cadmium red, Winsor blue, and yellow ochre for the final work. Here in China, the fine sable brushes recommended by Thompson are quite inexpensive.
Even just reading this book will help you understand art far better than the 99% of slobs who troop to the Mona Lisa at the Louvre, barbarically touching the sculptures and paintings with their apish paws (don't get me started...).