Question

What does the phrase "vale of yeares" most likely mean in these lines?
OTHELLO: Haply, for I am black
And have not those soft parts of conversation
That chamberers have, or for I am declined
Into the vale of years,—yet that's not much—
She's gone. I am abused; and my relief
Must be to loathe her. O curse of marriage, . . .
(from Othello by William Shakespeare)

a period of mourning
an age past one's prime
a period of religious zeal
a time of intense activity