They also serve who only stand and wait.
 Oliver Wendell Holmes Sr., Over the Teacups (1891). copy citation

Context

“The feeling must of necessity come to many aged persons that they have outlived their usefulness; that they are no longer wanted, but rather in the way, drags on the wheels rather than helping them forward. But let them remember the often-quoted line of Milton,
«They also serve who only stand and wait.»
This is peculiarly true of them. They are helping others without always being aware of it. They are the shields, the breakwaters, of those who come after them. Every decade is a defence of the one next behind it.” source

Meaning and analysis

write a note
report