Some of us fortunate enough to have published a paper in The Journal of Neuroscience in its inaugural year (1981) have been asked to write a Progressions article addressing our views on the significance of the original work and how ideas about the topic of that work have evolved over the last 40 years. These questions cannot be effectively considered without placing them in the context of the incredible growth of the overall field of neuroscience over these last four decades. For openers, in 1981, the Nobel Prize was awarded to three neuroscience superstars: Roger Sperry, David Hubel, and Torsten Wiesel. Not a bad year to launch the Journal . With this as a backdrop, I divide this Progressions article into two parts. First, I discuss our original (1981) paper describing classical conditioning in Aplysia californica , and place our results in the context of the state of the field at the time. Second, I fast forward to the present and consider some of remarkable progress in the broad field of learning and me...