to stand at their posts ready to meet the
fury of the unexpected gale? and yet the price of such great skill is
fully paid for by the passage money. At what sum can you estimate the
value of a lodging in a wilderness, of a shelter in the rain, of a bath
or fire in cold weather? Yet I know on what terms I shall be supplied
with these when I enter an inn. How much the man does for us who props
our house when it is about to fall, and who, with a skill beyond belief,
suspends in the air a block of building which has begun to crack at the
foundation; yet we can contract for underpinning at a fixed and cheap
rate. The city wall keeps us safe from our enemies, and from sudden
inroads of brigands; yet it is, well known how much a day a smith
would earn for erecting towers and scaffoldings [Footnote: See
Viollet-le-Duc's "Dictionnaire d'Architecture," articles "Architecture
Militaire" and "Hourds," for the probable meaning of "Propugnacula."]to
provide for the public safety.

XVI. I might go on for ever collecting instances to prove that valuable
things are sold at a low price. What then? why is it that I owe
something extra both to my physician and to my teacher, and that I do
not acquit myself of all obligation to them by paying them their fee? It
is because they pass from physicians and teachers into friends, and lay
us under obligations, not by the skill which they sell to us, but by
kindly and familiar good will. If my physician does no more than feel
my pulse and class me among those whom he sees in his daily rounds,
pointing out what I ought to do or to avoid without any personal
interest, then I owe him no more than his fee, because he views me with
the eye not of a friend, but of a commander. [Footnote: I read "Nbn
tamquam amicus videt sed tamquam imperator."] Neither have I any reason
for loving my teacher, if he has regarded me merely as one of the mass
of his scholars, and has not thought me worthy of taking especial pains
with by myself, if he has never fixed his attention upon me, and if when
he discharged his knowledge on the public, I might be said rather to
have picked it up than to have learnt it from him. What then is our
reason for owing them much? It is, not that what they have sold us is
worth more than we paid for it, but that they have given something to us
personally. Suppose that my physician has spent more consideration upon
my case than was professionally necessary; that it was for me, not for
his own