The book thus ushered into the world in 1785 treats of those constituents of the common sense that are implied, not only in perception of things through the five senses and memory, but also in imagination and in the experimental sciences that deal with the past, the distant, and the future. One of them contains the rudiments of a criticism of the common sense principles that finally regulate all abstract reasonings, and above all, those that determine our judgments of truths contingent upon Will—human and divine; in all of which what philosophers called ‘ideas’ seemed to him to spoil the genuine common sense and its inspirations. The fifth Essay deals with the office and relations of our abstract conceptions. Of this Essay Schopenhauer remarks that ‘the best and most intelligent exposition of the nature and essence of conceptions which I have been able anywhere to find is in Thomas Reid’s _Essays on the Powers of the Human Mind_. This was afterwards condemned by Dugald Stewart in his _Philosophy of the Human Mind_. Not to waste paper, I will briefly remark with regard to Stewart, that he belongs to that large class who have obtained an undeserved reputation through favour and friends, and therefore I can only advise that not an hour should be wasted over the scribbling of this shallow writer.’[23] This unworthy criticism of Stewart is far removed from the calm judgment of Reid. That our perceptions are not related to their objects as effects are related to their causes, is insisted on in the _Essays_, in opposition to Priestley, who treats cognitive acts as the issue of power which belongs to matter. ‘Men,’ Reid says, ‘have been prone to imagine that, as bodies are put in motion by some impulse or impression made upon them by contiguous bodies, so the mind is made to think and perceive by some impression made upon it by contiguous objects. But to say that an object which I see with perfect indifference _makes an impression_ upon my mind is not good English. It is evident from the manner in which this phrase is used by modern philosophers that they mean, not barely to express by it my perceiving an object, but to explain the manner of perception. They think that the object perceived acts upon the mind in some way similar to that in which one body acts upon another. The impression upon the mind is conceived to be something wherein the mind is altogether passive. But this is a hypothesis which contradicts the common sense of mankind. When I look upon the wall of my room, the wall does not act at all, nor is capable of acting: the perceiving it is an act or operation in me.’ In short, the relation between perceptions and their objects is a unique relation, not to be confounded with the causal, the only causality involved being the percipient power that is in me.