To overestimate the originality of one's thoughts is perhaps a less serious defect than being unaware of their newness. There is a more pronounced lack of sensitivity in underestimating (ourselves and others) than in overestimating.
It will go down in history as a turning point for the music industry. This is landmark stuff. I can't overestimate it!steve jobs
There is probably an element of malice in the readiness to overestimate people; we are laying up for ourselves the pleasure of later cutting them down to size.Eric Hoffer
The calculus was the first achievement of modern mathematics and it is difficult to overestimate its importance. I think it defines more unequivocally than anything else the inception of modern mathematics; and the system of mathematical analysis, which is its logical development, still constitutes the greatest technical advance in exact thinking.