You have all heard about the DNA double helix and genes. Many of you know that mutations occur randomly, that the DNA sequence is read by successive groups of three bases (the codons), that many genes encode enzymes, and that gene expression can be regulated. These concepts were proposed on the basis of astute genetic experiments, as well as often on biochemical results. The original articles were these concepts appeared are however not frequently part of the normal curriculum of biologists, biochemists and medical students. This course proposes to read study and discuss a small selection of these classical papers, and to put these landmarks in their historical context. Most of the authors displayed interesting personal histories and many of their contributions go beyond not only the papers we will read but probably all their scientific papers. Our understanding of the scientific process, of the philosophy underlying the process of scientific discovery, and on the integration of new concepts is not only important for the history of science but also for the mental development of creative science.