But our ideas of substances, being supposed copies, and referred to archetypes without us, must still be taken from something that does or has existed: they must not consist of ideas put together at the pleasure of our thoughts, without any real pattern they were taken from, though we can perceive no inconsistence in such a combination.

The reason whereof is because we, knowing not what real constitution it is of substances whereon our simple ideas depend, and which really is the cause of the strict union of some of them one with another, and the exclusion of others; there are very few of them that we can be sure are or are not inconsistent in nature: any further than experience and sensible observation reach Herein, therefore, is founded the reality of our knowledge concerning substances--That all our complex ideas of them must be such, and such only, as are made up of such simple ones as have been discovered to co-exist in nature.

And our ideas being thus true, though not perhaps very exact copies, are yet the subjects of real (as far as we have any) knowledge of them.

Which (as has been already shown) will not be found to reach very far: but so far as it does, it will still be real knowledge.

Whatever ideas we have, the agreement we find they have with others will still be knowledge.