In which way of substitution it has so confused and uncertain a signification, that, though this proposition--'gold is fixed'-- be in that sense an affirmation of something real; yet it is a truth will always fail us in its particular application, and so is of no real use or certainty.

For let it be ever so true, that all gold, i.e.all that has the real essence of gold, is fixed, what serves this for, whilst we know not, in this sense, WHAT IS OR IS NOT GOLD?
For if we know not the real essence of gold, it is impossible we should know what parcel of matter has that essence, and so whether IT be true gold or no.
51.

Conclusion.
To conclude: what liberty Adam had at first to make any complex ideas of MIXED MODES by no other pattern but by his own thoughts, the same have all men ever since had.

And the same necessity of conforming his ideas of SUBSTANCES to things without him, as to archetypes made by nature, that Adam was under, if he would not wilfully impose upon himself, the same are all men ever since under too.

The same liberty also that Adam had of affixing any new name to any idea, the same has any one still, (especially the beginners of languages, if we can imagine any such;) but only with this difference, that, in places where men in society have already established a language amongst them, the significations of words are very warily and sparingly to be altered.