I learned a new word: perspicuous

Perspicuous: (adj) 1. Clearly expressed or presented; lucid.

From "An Inquiry into the Nature and Causes of the Wealth of Nations", Adam Smith

"The word VALUE, it is to be observed, has two different meanings, and
sometimes expresses the utility of some particular object, and sometimes
the power of purchasing other goods which the possession of that object
conveys. The one may be called 'value in use;' the other, 'value
in exchange.' The things which have the greatest value in use have
frequently little or no value in exchange; and, on the contrary, those
which have the greatest value in exchange have frequently little or no
value in use. Nothing is more useful than water; but it will purchase
scarce any thing; scarce any thing can be had in exchange for it. A
diamond, on the contrary, has scarce any value in use; but a very great
quantity of other goods may frequently be had in exchange for it.

In order to investigate the principles which regulate the exchangeable
value of commodities, I shall endeavour to shew,

First, what is the real measure of this exchangeable value; or wherein
consists the real price of all commodities.

Secondly, what are the different parts of which this real price is
composed or made up.

And, lastly, what are the different circumstances which sometimes raise
some or all of these different parts of price above, and sometimes sink
them below, their natural or ordinary rate; or, what are the causes
which sometimes hinder the market price, that is, the actual price
of commodities, from coinciding exactly with what may be called their
natural price.

I shall endeavour to explain, as fully and distinctly as I can, those
three subjects in the three following chapters, for which I must very
earnestly entreat both the patience and attention of the reader: his
patience, in order to examine a detail which may, perhaps, in some
places, appear unnecessarily tedious; and his attention, in order to
understand what may perhaps, after the fullest explication which I am
capable of giving it, appear still in some degree obscure. I am always
willing to run some hazard of being tedious, in order to be sure that
I am perspicuous; and, after taking the utmost pains that I can to be
perspicuous, some obscurity may still appear to remain upon a subject,
in its own nature extremely abstracted."