we should be guided by analogy in our conclusions as well as in the acceptation of words.
Convinced, therefore, that classes or sorts of things are pure denominations, we shall never think of supposing that there exist in nature genera or species; and we shall understand by these words nothing but a certain mode of classing things according to the relations which they have to ourselves and to one another. We shall be sensible that we can only discover those relations, and not what the things truly are."
Berkeley handled his subjects with little tenderness, and he has perfectly anatomised this subject of abstract ideas. In choosing to answer the objections to this doctrine as stated by him, I shall not be accused of wishing to encounter a mean adversary. I can only trust to the goodness of my cause. I hope I shall be excused for going at some length into the argument, because it is one of the most difficult and complicated in itself, and is of the most extensive application to other questions relating to the human understanding. If we can come to any satisfactory issue to it, it will be worth the pains of enquiry.
"It is agreed on all hands," says this author, "that the quantities or modes of things do never really exist in each of them, apart by itself, and separated from all others, but are mixed, as it were, and blended together, several in the same object. But we are told the mind being able to consider each quality singly, or abstracted from those other qualities with which it is united, does by that means frame to itself abstract ideas. For example, there is perceived by sight, an object, extended, coloured, and moved. This mixed idea the mind resolving into its simple constituent parts, and viewing each by itself exclusive of the rest, does frame the abstract ideas of extension, colour, and motion.
