Arthur Hugh Clough Quote

Go; say not in thy heart, And what then were it accomplished,
Were the wild impulse allayed, what were the use or the good!
Go, when the instinct is stilled, and when the deed is accomplished,
What thou bast done and shalt do, shall be declared to thee then.
Go with the sun and the stars, and yet evermore in thy spirit
Say to thyself: It is good: yet is there better than it.
This that I see is not all, and this that I do is but little;
Nevertheless it is good, though there is better than it.

Hope Evermore and Believe!, st. 2 (written 1853, published 1862).