Now from his breast into his eyes the ache of longing mounted, and he wept at last,
his dear wife, clear and faithful, in his arms,
longed for
as the sunwarmed earth is longed for by a swimmer
spent in rough water where his ship went down
under Poseidon’s blows, gale winds and tons of sea.
Few men can keep alive through a big surf
to crawl, clotted with brine, on kindly beaches
in joy, in joy, knowing the abyss behind (436).

The author is comparing the way Odysseus: to the way:
The comparison illustrates [explain connotative meaning of his emotional state]
because [explain the connotation as suggested by the comparison].