This book was first published in 1958, and if anything it is more relevant today. It is a long, subtle and detailed book, one you cannot rush, just like a fine old wine. Polanyi was a distinguished physical chemist, and a Fellow of the Royal Society, and this work was his extended and articulate rebuttal of the positivist account of science that was prevalent then and is growing again now.
Many (most) people today have only a very hazy idea of what proper scientific method is, and what characterises good science practise. Polanyi shows that far from being all cut and dried as popular mythology would have it, the progress of science depends to a much greater extent than commonly recognised on what he calls "tacit knowledge": the hunch, the smell of a problem, a sense of how it ought to be.
If you want to know how science really works, from a master of the art, and you like engaging in profound thought, then this book is for you.