May it not be the same for the faculty of conception? May not the word “general idea” or “concept” be in its kind the equivalent of the word image, namely a vague formula,—its psychological reality lying in types or variations as yet undetermined? I am exposing for ideas, the problem that has already been set forth for images, while recognising its much greater obscurity. The psycho-physiological conditions of the existence of concepts are practically unknown: this is a _terra incognita_ wherein the new psychology has hardly adventured itself, and where it would indeed have been chimerical to tread before the preliminary study of the image. I. The question I have set myself to elucidate is very modest, very limited and circumscribed, representing only part of the problem indicated above. It may, however, teach us something of the ultimate nature of concepts. It is as follows: When we think, hear, or read a general term, what arises as sign in consciousness, _directly and without reflexion_? I have purposely italicised these words in order to emphasise my principal aim, which was to discover the _instantaneous_ operations (conscious or unconscious) that occur in such a case, in persons whose habits of mind are widely different. I endeavored as much as possible to eliminate reflexion and to seize the mental state. With time and effort, minds that are least apt in abstraction will arrive at a more or less successful translation of general terms, or at the substitution for them of some mangled and halting definition. I set myself as far as possible to suppress this secondary phase of the mental process, and to arrest it at the first, in order to determine what the word evokes immediately[80] and in what degree this differs with the individual. In order to make the answers more exactly comparable, I interrogated only the adults of both sexes, excluding all children. It was indispensable to my investigation that it should comprise people of very different degrees of culture, habits of mind, and profession. The principal classes were mathematicians, physicists, doctors, scientists, philosophers, painters, musicians, architects, men of the world, women, novelists, poets, artisans. The last class made such confused replies that I must regard their documents as worthiest. Too much is left for individual interpretation. The total number of persons interrogated amounted to one hundred and three.