Nature and man can never be fast friends.

And this brings us to the idea of Duty as set forth in his poems, and
Duty resolves itself into three main elements: Truth--Work--Love. Truth
comes first. Man's prime duty is to know things as they are. Truth can
only be attained by light, and light he must cultivate, he must worship.
Arnold's highest praise for a lost friend is that he was "a child of
light"; that he had "truth without alloy,"

And joy in light, and power to spread the joy.

The saddest part of that friend's death is the fear that it may bring,

After light's term, a term of cecity:

the best hope for the future, that light will return and banish the
follies, sophistries, delusions, which have accumulated in the darkness.
"Lucidity of soul" may be--nay, must be, "sad"; but it is not less
imperative. And the truth which light reveals must not only be sought
earnestly and cherished carefully, but even, when the cause demands it,
championed strenuously. The voices of conflict, the joy of battle, the
"garments rolled in blood," the "burning and fuel of fire" have little
place in Arnold's poetry. But once at any rate he bursts into a strain
so passionate, so combatant, that it is difficult for a disciple to
recognize his voice; and then the motive is a summons to a last charge
for Truth and Light--

They out-talk'd thee, hiss'd thee, tore thee?
Better men fared thus before thee;
Fired their ringing shot and pass'd,