But it is plain that in our complex ideas of substances are not contained such ideas, on which all the other qualities that are to be found in them do depend.  The common idea men have of iron is, a body of a certain colour, weight, and hardness; and a property that they look on as belonging to it, is malleableness.  But yet this property has no necessary connexion with that complex idea, or any part of it:  and there is no more reason to think that malleableness depends on that colour, weight, and hardness, than that colour or that weight depends on its malleableness.  And yet, though we know nothing of these real essences, there is nothing more ordinary than that men should attribute the sorts of things to such essences.  The particular parcel of matter which makes the ring I have on my finger is forwardly by most men supposed to have a real essence, whereby it is gold; and from whence those qualities flow which I find in it, viz. its peculiar colour, weight, hardness, fusibility, fixedness, and change of colour upon a slight touch of mercury, &c.  This essence, from which all these properties flow, when I inquire into it and search after it, I plainly perceive I cannot discover:  the furthest I can go is, only to presume that, it being nothing but body, its real essence or internal constitution, on which these qualities depend, can be nothing but the figure, size, and connexion of its solid parts; of neither of which having any distinct perception at all can I have any idea of its essence:  which is the cause that it has that particular shining yellowness; a greater weight than anything I know of the same bulk; and a fitness to have its colour changed by the touch of quicksilver.  If any one will say, that the real essence and internal constitution, on which these properties depend, is not the figure, size, and arrangement or connexion of its solid parts, but something else, called its particular form, I am further from having any idea of its real essence than I was before.  For I have an idea of figure, size, and situation of solid parts in general, though I have none of the particular figure, size, or putting together of parts, whereby the qualities above mentioned are produced; which qualities I find in that particular parcel of matter that is on my finger, and not in another parcel of matter, with which I cut the pen I write with.  But, when I am told that something besides the figure, size, and posture of the solid parts of that body in its essence, something called substantial form, of that I confess I have no idea at all, but only of the sound form; which is far enough from an idea of its real essence or constitution.  The like ignorance as I have of the real essence of this particular substance, I have also of the real essence of all other natural ones:  of which essences I confess I have no distinct ideas at all; and, I am apt to suppose, others, when they examine their own knowledge, will find in themselves, in this one point, the same sort of ignorance.