They also serve who only stand and wait

My father used to sometimes quote these lines but until today I did not look them up and understand their context. I never knew he had such a good knowledge of Milton either, but there are unfathomed depths to each human being. It expresses a nice sentiment on the virtue of humility.

They also serve who only stand and wait

It is a quotation from the great English poet John Milton (1608-74). After going blind, Milton wrote the poem "On His Blindness". In the sonnet's last line, he reflects that even with his disability he has a place in the world:

When I consider how my light is spent

Ere half my days in this dark world and wide,

And that one Talent which is death to hide

Lodged with me useless, though my soul more bent

To serve therewith my Maker, and present

My true account, lest He returning chide,

"Doth God exact day-labour, light denied?"

I fondly ask. But Patience, to prevent

That murmur, soon replies, "God doth not need

Either man's work or his own gifts. Who best

Bear his mild yoke, they serve him best. His state

Is kingly: thousands at his bidding speed,

And post o'er land and ocean without rest;

They also serve who only stand and wait.

Meaning: We all have a place in this world and we all perform a function, regardless of our ability or disability (although Talent here refers to the parable from Jesus of the three Talents). The word order of this sentence may make it more difficult to understand. In normal English it would be something like: "They (those people) who only stand and wait, also serve."