Husserl's Logical Investigations can be characterized as an attempt to determine the relation between idealities and contingent facts. According to ancient tradition, in which, as Husserl points out in his Crisis,the idea of science originated, philosophy deals with idealities. Ordinary experience is quite rough. Everyday experience shows, for instance, that ravens are black, but that there are also albinos which are white. Normally, summers are dry and hot and winters are cold, but we all know that this is not really certain. Thus we have to admit that judgments of ordinary experience are valid only with a certain kind of probability. It was therefore a great discovery when philosophers realized that there are also judgments which have the character of certainty. Such judgments were first developed by mathematics. Socrates, the first philosopher, who asked for definitions, extended it to linguistic analysis. Plato systematized it in his dialectics and his doctrine of ideas, and his pupil Aristotle invented formal logic which allowed the drawing of conclusions from true premises which are necessarily true. The problem is, however, that we gain certainty not in regard to contingent facts but only in regard to idealities. This leads to the conception of ideal essences which are conceived as the reliable structure on which the contingent appearances grow. In this early stage in the history of science, genuine science was conceived as dealing with such ideal essences.