Philosophy is not an advance or correction of science. In so far as the latter claims to be absolutely or philosophically true, substantialism abolishes it in dispensing with the notions of real matter and real space. Hence it is quite irrelevant to point out that substantialism is inconsistent with (say) the doctrine of physical evolution. This theory, though so new, is now often referred to as axiomatically true, whereas it is an inference, the evidence for which, even to many realists, is far from conclusive. Whether it be considered true or not in science, physical evolution is quite untrue in philosophy. IDEAS VIII--HOW PRODUCED An imprint or mould of the object is generally left in the plasma of the subject. The imprint is deep, clear and lasting in proportion to the strength of the exciting cause and the degree of energy assigned to the perception. When the noumenon withdraws the object does not at once disappear, for if the energy of attention remain the mould left by the noumenon serves to excite a consciousness similar to the object, and this is what we call an IDEA. What Hume says as to an object differing from an idea in nothing but vividness is evidently incorrect. Objects are generally, but not always, more vivid than ideas, and when an object is present we have an indefeasible conviction of being acted on by something not ourselves, which conviction is not present in recollection. We may not be able to give a satisfactory reason for the conviction--if we are arguing idealistically we certainly shall not--but the fact that it is there serves to mark off objects as a class of consciousness distinct from ideas, irrespective of their vividness. If an object were once seen clearly and so remembered, and were afterwards seen indistinctly through a mist, the latter consciousness would (according to Hume) be the idea and the former the object. Such an application of words would be an abuse of language. There are of course no innate ideas of _objects_. There is innate consciousness--the sentimental. Ideas are of three kinds--Particular Ideas, General Ideas, Imaginary Ideas--corresponding to the so-called faculties of Memory, Generalisation or Classification, and Imagination. IX--MEMORY OF OBJECTS When the energy of attention is exhausted or withdrawn the idea also disappears, but it may be revived by bringing the energised Self in contact with the imprint again, and this operation can be repeated indefinitely. The power of exciting ideas of past experience is Memory; any particular exercise of memory is Recollection.