Conceptual matter is the iron which we, as thinkers, have to forge. Many kinds of implements must be made thereof; for digging, for ploughing, for fighting, for forging itself. Scientific thought is not a matter of chance. It must be learned by hard work and practised in persistent endurance and eager striving; its rules and methods must be known. Natural capacity is called for, as for every other art; but even the most capable will go astray if he allows himself to be led by, or encouraged in, the fancy that philosophy must be characterised by lively intuition, fancy, and poetic diction, instead of by exact and strict thought.
But we think that an honest endeavour to find a deeper basis for these branches of knowledge, even though its success should not be recognised, deserves at least to be respected as good will, and we venture to appropriate the utterance of a famous predecessor: “The consideration then,” says John Locke (Essay on Human Understanding, iv., 21, 4), “of ideas and words, as the great instruments of knowledge, makes no despicable part of their contemplation, who would take a view of human knowledge, in the whole extent of it. And perhaps, if they were distinctly weighed and duly considered, they would afford us another sort of logick and critick than what we have been hitherto acquainted with.” And with reference to the utility of the treatise, again, we may say with him (ibid., iii., 5, 16): “I shall imagine I have done some service to truth, peace and learning, if by any enlargement on this subject, I can make men reflect on their own use of language; and give them reason to suspect, that, since it is frequent for others it may also be possible for them, to have sometimes very good and approved words in their mouths and writings, with very uncertain, little or no signification. . . . And therefore, it is not unreasonable for them, to be wary herein to themselves, and not to be unwilling to have them examined by others.”
I.
1. We call an object (A) the sign of another object (B), when the perception or recollection A has the recollection B for its regular and immediate consequence. By object we mean here everything which can enter into a perception or recollection, things therefore as well as events. Perception is all apprehension through sense; recollection includes, besides the reproduction of perceptions, the reproduction of all other sensations in so far as they have an object, or at any rate a content which can be regarded as object. Human recollec-
