No man knows his own voice; many men do not know their own profiles.
 Oliver Wendell Holmes Sr., The Autocrat of the Breakfast-Table (1858). copy citation

Context

“It may be questioned whether anything can be conscious of its own flavor. Whether the musk-deer, or the civet-cat, or even a still more eloquently silent animal that might be mentioned, is aware of any personal peculiarity, may well be doubted. No man knows his own voice; many men do not know their own profiles. Every one remembers Carlyle’s famous “Characteristics” article; allow for exaggerations, and there is a great deal in his doctrine of the self-unconsciousness of genius. It comes under the great law just stated.” source