 We have just considered two points of disagreement over the nature of instinct that arose in the late 19th century as this concept was gaining in scientific currency. In fact, Morgan (1895) identified a total of seven “definitional” issues surrounding the instinct concept in his day. It is noteworthy, given how fecund the concept of instinct was in motivating scientific research between 1880–1900, that instinct was already being criticised for its ambiguity. Morgan expressed his frustration with this situation in the following, frequently cited passage: