There is a kind of proportion. As gentleness is to power, so liberality (in the sense here used) is to obedience. Now gentleness is the check on the excess of power; therefore liberal here applies to that which checks the excess of obedience, i.e. checks servility. Hence liberal here means "free."
The contrast also adds force. "They aimed at the rule(a), not at the destruction(a'), of their country. They were men of great civil(b) and great military(b') talents, and, if the terror(c), the ornament(c') of their age."
Excessive antithesis is unnatural and wearisome:—
"Who can persuade where treason(a) is above reason(a'), and might(b) ruleth right(b'), and it is had for lawful(c) whatsoever is lustful(c'), and commotioners(d) are better than commissioners(d'), and common woe(e) is named common wealth(e')?"
*42. Epigram.*—It has been seen that the neglect of climax results in lameness. Sometimes the suddenness of the descent produces amusement: and when the descent is intentional and very sudden, the effect is striking as well as amusing. Thus:—
(1) "You are not only not vicious, you are virtuous," is a climax.
(2) "You are not vicious, you are vice," is not climax, nor is it bathos: it is epigram.[15]
Epigram may be defined as a "short sentence expressing truth under an amusing appearance of incongruity." It is often antithetical.
"The Russian grandees came to { and diamonds," climax.
court dropping pearls { and vermin," epigram.
"These two nations were divided { and the bitter remembrance
by mutual fear { of recent losses," climax.
{ and mountains," epigram.