We have already noticed the inadequacy of the definition which describes science as organised common-sense. We ought perhaps rather to define it as organised knowledge. Such a definition makes it clear that the first stage in the development of any science must necessarily be the accumulation of facts. The facts may be either particular or universal. Some sciences, such as botany and pathology, still find it important to record exceptional and unusual occurrences which at first sight appear to form exceptions to the general scheme of nature. In the more exact and more highly developed sciences, such as physics and astronomy, there are none such to record; here nature appears to be governed by immutable laws. The aim of science is to discover and interpret these laws.

Scientific Synthesis

When a sufficient number of facts have been collected in any particular branch of science, the next stage is to try and cover them all by a general principle, which may or may not admit of an explanation in terms of familiar concepts. To be ultimately satisfactory, such a general principle or explanation must not only cover all the facts already known, but also all the facts which remain to be found out. It is accordingly first put forward in the form of a hypothesis. A scientist says in effect—“Observation shews that the following facts are true; I find that a certain hypothesis as to their origin is consistent with them all”.