Because I oft in dark abstracted guise
Seem most alone in greatest company,
With dearth of words, or answers quite awry,
To them that would make speech of speech arise,

They deem, and of their doom the rumor flies,
That poison foul of bubbling pride doth lie
So in my swelling breast that only I
Fawn on myself, and others do despise:

Yet pride I think doth not my soul possess,
Which looks too oft in his unflatt'ring glass:
But one worse fault, ambition, I confess,

That makes me oft my best friends overpass,
Unseen, unheard, while though to highest place
Bends all his powers, even unto Stella's grace.

Sir Philip Sidney

http://www.poemhunter.com/poem/sonnet-xxvii-because-i-oft/