Let us examine in its turn the physical process which is supposed to be discovered in my nervous centres while I am in course of contemplating the landscape. This pretended physical process itself, quite as much as my conscious perception of the landscape, is a physico-psychical phenomenon; for my cerebral movements are perceived, hypothetically at least, by an observer. This is a perception, consequently it can be decomposed into two things, a consciousness and its object. As a further consequence, when we wish, by a metaphysical effort, to attach the consciousness to a material state of the brain and to establish a link between the two events, it will be found that we wrongly hook one physico-mental phenomenon on to another. But, evidently, this objection is not a refutation. We may if we choose suppose that the so-called cerebral process is capable of subsisting at moments when no one perceives it, and that it exists of itself, is sufficient for itself, and is entirely physical. But can we subject the mental process of perception to the same purification? Can we separate these two elements, the consciousness and its object, retain the element consciousness and reject the element object, which is physical, thus constituting a phenomenon entirely mental, which might then be possibly placed beside the entirely physical phenomenon, so as to study their relation to each other? This is quite impossible, and the impossibility is double, for it exists _de facto_ and _de jure_. _De jure_, because we have already established that a consciousness empty and without object cannot be conceived. _De facto_, because the existence of the object that consciousness carries with it is very embarrassing for the materialist; for this object is material, and as real and material as the fibres and cells of the brain. It might, indeed, be supposed that by transformation or otherwise there goes forth from the cerebral convolution a purely psychical phenomenon resembling a wave. But how can we conceive the transformation of this convolution into a semi-material phenomenon? How can we comprehend that there should issue from this convolution the material object of a perception--for example, a plain dotted with houses?