" we
consider a little what the good, of mankind is.

I take it that the good of mankind means the attainment, by every
man, of all the happiness which he can enjoy without diminishing the
happiness of his fellow-men.[1]

[Footnote 1: "Hie est itaque finis ad quem tendo, talem scilicet
Naturam acquirere, et ut multi mecum eam acquirant, conari hoc est
de mea felicitate etiam operam dare, ut alii multi idem atque ego
intelligant, ut eorum intellectus et cupiditas prorsus cum meo
intellectu et cupiditate convenient: atque hoc fiat, necesse est
tantum de Natura intelligere, quantum sufficit ad talem naturam
acquirendam; deinde formare talem societatem qualis est desideranda,
ut quam plurimi quam facillime et secure eo perveniant."--B. SPINOZA,
_De Intellectus Emendatione Tractatus._]

If we inquire what kinds of happiness come under this definition, we
find those derived from the sense of security or peace; from
wealth, or commodity, obtained by commerce; from Art--whether it
be architecture, sculpture, painting, music, or literature; from
knowledge, or science; and, finally, from sympathy or friendship. No
man is injured, but the contrary, by peace. No man is any the worse
off because another acquires wealth by trade, or by the exercise of
a profession; on the contrary, he cannot have acquired his wealth,
except by benefiting others to the full extent of what they considered
to be its value; and his wealth is no more than fairy gold if he does
not go on benefiting others in the same way. A thousand men may enjoy
the pleasure derived from a picture, a symphony, or a poem, without
lessening the happiness of the most devoted connoisseur. The
investigation of nature is an infinite pasture-ground, where all
may graze, and where the more bite, the longer the grass grows, the
sweeter is its flavour, and the more it nourishes. If I love a friend,
it is no damage to me, but rather a pleasure, if all the world also
love him and think of him as highly as I do.

It appears to be universally agreed, for the reasons already
mentioned, that it is unnecessary and undesirable for the State
to attempt to promote the acquisition of wealth by any direct
interference with commerce. But there is no such agreement as to the
further question whether the State may not promote the acquisition of
wealth by indirect means. For example, may the State make a road, or
build a harbour, when it is quite clear that by so doing it will open
up a prod