The epistemological priority of consciousness in modern philosophy, starting with Descartes, brings with it a new understanding of ideas that, in contrast to the Platonic conception, become the immediate objects of the mind. This stand-point is also accepted by the line of the British empirical sensationalism that comprises Locke, Berkeley and Hume. In Locke ideas still have what might be called a representative character – they refer to assumed existences outside consciousness (real essences). Berkeley, rejecting any sort of materiality, anticipates to a degree Hume’s sceptical position where there is a conscious abandonment of any attempt to seek the origin of perceptions. Hume divides perceptions into impressions (original sense data) and ideas (which are derived from impressions as their copies). Perception works with the first; imagination and thinking with the second. In addition to impressions being primary and ideas secondary, the two kinds of perceptions differ from one another in their strength and vivacity, which are higher in impressions. This seemingly simple doctrine brings with it, however, many problems and objections. In spite of the variety of critical viewpoints, among which straightforward misunderstandings are included, most commentators agree that Hume is interested not so much in a theory as in a procedural rule (allowing the possibility of exceptions), and that Hume’s originality does not consist in this psychological foundation, which he more or less took over from his precursors, but more especially in his deep and penetrating analyses.