And is the only way in which the meaning of mixed Modes can be made known.
Another reason that makes the defining of mixed modes so necessary, especially of moral words, is what I mentioned a little before, viz.
that it is the only way whereby the signification of the most of them can be known with certainty.

For the ideas they stand for, being for the most part such whose component parts nowhere exist together, but scattered and mingled with others, it is the mind alone that collects them, and gives them the union of one idea: and it is only by words enumerating the several simple ideas which the mind has united, that we can make known to others what their names stand for; the assistance of the senses in this case not helping us, by the proposal of sensible objects, to show the ideas which our names of this kind stand for, as it does often in the names of sensible simple ideas, and also to some degree in those of substances.
19.

In Substances, both by showing and by defining.
III.

Thirdly, for the explaining the signification of the names of substances, as they stand for the ideas we have of their distinct species, both the forementioned ways, viz.

of showing and defining, are requisite, in many cases, to be made use of.