There are three aspects of thinking as more or less complete stages of it. These are, conception, judgment, and reasoning. They are not to be considered three distinct acts; not even three successive stages. No one of them could occur without each of the others.
Conception is taking together into one idea the element of meaning common to a number of objects and things. ...Conception is... the simplest act of thinking; it is the apprehension of the universal, as perception is the apperception of the particular. We perceive this man; we conceive man. ...it is universal through its ideal element, or what it points to, not from its existence.
Concepts have meaning only if we can point to objects to which they refer and to rules by which they are assigned to these objects.
Concepts can only acquire content when they are connected, however indirectly, with sensible experience. But no logical investigation can reveal this connection; it can only be experienced. ...this connection ...determines the cognitive value of systems of concepts.
The aim of science is... a comprehension, as complete as possible, of the connection between the sense experiences in their totality, and... the accomplishment of this aim by the use of the minimum of primary concepts and relations.
All concepts, even those which are closest to experience, are from the point of view of logic freely chosen conventions.
Often it is only after immense intellectual effort, which may have continued over centuries, that humanity at last succeeds in achieving knowledge of a concept in its pure form, by stripping off the irrelevant accretions which veil it from the eye of the mind.
Concepts, like individuals, have their histories, and are just as incapable of withstanding the ravages of time as are individuals.
Kant says that concept without percepts are empty, percepts without concepts are blind; it would perhaps be truer to say that concepts and percepts are inseparable; and if torn asunder, they are nothing.