19. The common feature of everything psychical consists in what has been called by a very unfortunate and ambiguous term, consciousness; i.e. in a subject-attitude; in what has been termed an _intentional_ relation to something which, though perhaps not real, is none the less an inner object of perception[19] No hearing without the heard, no believing without the believed, no hoping without the hoped for, no striving without the striven for, no joy without the enjoyed, and so with other mental phenomena. 20. The sensuous qualities which are given in our impressions with physical content exhibit manifold differences. So also do the intentional relations given in our impressions with psychical content. And, as in the former case, the number of the senses is determined by reference to those distinctions between sensuous qualities which are most fundamental (called by Helmholtz distinctions of modality), so in the latter case the number of fundamental classes of mental phenomena is fixed by reference to the most fundamental distinctions of intentional relation.[20] In this way we distinguish three fundamental classes. Descartes in his _Meditations_[21] was the first to exhibit these rightly and completely; but sufficient attention has not been paid to his observations, and they were soon quite forgotten, until in recent times, and independently of him, these were again discovered. Nowadays they may lay claim to sufficient verification.[22] The first fundamental class is that of ideas (Vorstellungen) in the widest sense of the term (Descartes’ ideae). This class embraces concrete impressions, those for example which are given to us through the senses, as well as every abstract conception. The second fundamental class is judgment (Descartes’ judicia). Previous to Descartes these were thought of as forming, along with ideas, _one_ fundamental class, and since Descartes’ time philosophy has fallen once more into this error. This view regarded judgment as consisting essentially in a combination or relation of ideas to one another. This was a gross misconception of its true nature. We may combine or relate ideas as we please, as in speaking of a golden mountain, the father of a hundred children, a friend of science; but as long as nothing further takes place there can be no judgment. Equally true is it that an idea always forms the basis of a judgment, as also of a desire; but it is not true that, in a judgment, there are always several ideas related to one another as subject and predicate. This is certainly the case when I say: “God is just,” though not when I say: “There is a God.”