A fully-fledged doctrine of signs, with many horizons for the future, was the result of Thomas A. Sebeok's work in the twentieth century. This volume, using the testimonies of key witnesses and participants in the semiotic project, offers a picture of how Sebeok, through his development of knowledge of endosemiotics, phytosemiotics, biosemiotics and sociosemiotics, enabled semiotics in general to redraw the boundaries of science and the humanities as well as nature and culture.