Michel Thellier has had a career of professor in plant physiology and biophysics at the University. He has been the Chief Editor of the American journal “J. Trace Microprobe Techniques” and the Associate Editor of the series “Biology” of the proceedings of the French Academy of Science. He has been the author or editor of a dozen books dealing with plant and cell biology. He is a Member of the French Academy of Science and of the French Academy of Agriculture. All along his career, he has taken a particular interest in plant sensitivity to stimuli. Today, he wishes to help people understand how plant can possess a real capacity of memory, which is, both, so different from ours and so well adapted to the characteristics of its close environment.