Notes

1] The date of composition is uncertain, Milton's blindness, to which this is the first reference in his poetry, became virtually complete in 1652, but if the arrangement of his sonnets is (as it elsewhere appears to be) chronological, the date must be, like that of Sonnet XVIII, 1655. First printed in Poems, 1673.
light: power of vision, to be taken in conjunction with "this dark world." In a letter of 1654 Milton refers to a very faint susceptibility to light still remaining to him.

2] Ere half my days: we must not expect mathematical accuracy. But if we remember that Milton is speaking about his career in God's service, take its beginning in the avowed dedication to that service in Sonnet VII (1632), and assume the scriptural life-span of three score years and ten (which would mean life till 1678), 1652 falls before, and even 1655 does not extend beyond, the half-way mark of Milton's expected career of service.

3-6] The allusion is to the parable of the talents (Matthew 25:14-30); death, like the outer darkness into which the unprofitable servant was cast, stands for the utmost in punishment; the Talent was a measure of weight and hence of value; there is here, of course, a play on the word in its modern sense of mental gift or endowment, in Milton's case his gift of poetry.

8] fondly: foolishly.

Other poems by John Milton