The work of abstraction by which, treating the facts directly known as so much material for framing explanations, we pass from these actual facts to the general laws which explain them, falls into four stages, and at each stage, according to Bergson, as we go further and further from the original fact directly known, the two vices of the intellectual method, limitation and distortion of the actual fact, become more and more apparent. Starting from the fact directly known, the first thing, as we have seen, is to learn to distinguish common qualities which it shares in common with some, but not all, other facts; the next thing is to classify it by fitting it into the further groups to which these various qualities entitle it to belong. The moment a quality has been distinguished in a fact that fact has been fitted into a class, the class which consists of all the facts in which that quality can be distinguished. Thus, in our original illustration, when you first distinguished warmth, etc., you were beginning to fit your fact into classes: when you perceived warmth you fitted it into the class of warm objects, and it was the same with the other qualities of roughness, size and smell. This fitting of facts into classes according to the common qualities distinguished in them might be called a preliminary classification, but we shall use the term analysis for this preliminary grouping of facts according to their qualities, keeping the term classification for the next step, which you took when you realized “this is a dog,” which consists in the discovery not of mere disconnected qualities but of “real things.” Just as every quality, such as “warm” or “hairy” or “sweet” or “cold” is a class of actual facts, so every “real thing” such as “a dog” or “an ice cream” is a class of qualities. Thus a quality is once, and a “real thing” is twice, removed from actual fact, and the more energetically we pursue the intellectual work of abstraction the further we get from the fact itself from which we began. The point of grouping facts into classes, whether by analysing them into qualities or classifying them into “real things,” is that we can then apply to the particular fact all that we know to be true in general of whatever belongs to these various classes: in a word, once we have fitted a fact into a class we can apply to it all the general laws which are known to apply to that class.