218 STR WILLIAM HAMILTON'S PHILOSOPHY. 



answer is well worthy of consideration by those who would compre- 

 hend his theory. To Hume the sjime problem presented itself, but 

 rnet with a very different solution. According to his theory 

 regarding the origin of mental phenomena, these are all, to 

 use his own language, either impressions or ideas, or, to use lan- 

 guage which he might have adopted if he had not been too timid 

 in departing from that of ordinary literature, presentations or 

 representations. Still further, according to that theory, our repre- 

 sentations can never contain any element which has not been first 

 given in a presentation ; and therefore any idea or representation 

 which we form of existence must be derived from some impression or 

 presentation. But there is no presentation of existence as an object 

 of knowledge, uniformly accompanying the presentation of those ob- 

 jects to which we attribute existence ; and consequently, " the idea of 

 existence is the very same with the idea of what we conceive to be 

 existent. Any idea, therefore, we please to form is the idea of a 

 being, and the idea of a being is any idea we please to form." Ac- 

 cordingly, " we can never conceive any kind of existence, but those 

 perceptions which have appeared within the narrow compass of our 

 own minds."* But our minds themselves? It is evident that " what 

 we call a mind is nothing but a heap or collection of different per- 

 ceptions, united tt'tgether by certain relations, and supposed, though 

 falsely, to be endowed with a perfect simplicity and identity. "f I 

 shall not here anticipate a criticism that will more appropriately arise 

 at a subsequent part of these discussions, when we shall find the simi- 

 larity between the theory of Hume and the latest form of empiricism 

 in their explanation of all known existence as a series of presentations 

 and representations. 



When the Treatise of Human Nature STpjieared in 173I>, Thomas 

 Reid, who was a year older than Hume, had been already two years 

 a clergyman of the Scotch church in the parish of New Machar in 

 Aberdeenshire. Descended on the father's side from a family, which 

 for some generations had been distinguished in the literature and in 

 the learned professions, especially in the church, of Scotland ; on the 

 mother's side, a nephe<v of David Gregory, the celebrated Savilian 

 professor of Astronomy at Oxford and personal friend of Sir Isaac 

 Newton, Reid continued to follow his ancestral scientific tastes with 



* Treatise, Book I., Chap. 2, Sec. 6. 

 flbid, Book I., Chap. 4., Sec. 2. 



