A most difficult science?

(Thomas Reade, "Christian Experience")

The knowledge of ourselves is a most
difficult science, owing to the vanity of
our minds, and the influence of 'self love'.

We are blind to our own faults, but
quick sighted to the failings of others.

The mote in our brother's eye is readily
discerned, while we are unconscious of
the beam so apparent in our own.