The Progression of Categories
"The first step from sensation to perception is made by an ordering process that depends upon the presence in our experience of certain primary data. We shall define as the categories those elements of experience that on the one hand are given immediately, and on the other appear to have a general or universal character. The categories are the means whereby we begin to construct from our immediate experience an orderly picture of our world. They are thus at once the completion of perception and the start of reasoning. When we begin to reason, we fix our attention upon the categories and seek to express the meanings they bear for us by means of words or symbols. The formula so constructed can be called the principles. The categories, being the elements of our immediate experience and therefore certain, are concrete; whereas the principles, being the expression of our comprehension of these elements, are abstract and therefore subject to our own uncertainties and limitations."