The man who underestimates himself is perpetually being surprised by success, whereas the man who overestimates himself is just as often surprised by failure. The former kind of surprise is pleasant, the latter unpleasant. It is therefore wise to be not unduly conceited, though also not too modest to be enterprising.
Bertrand Russell (1872-1970) English mathematician and philosopher
Conquest of Happiness, Part 2, ch. 10 “Is Happiness Still Possible?” (1930)
(Source)
Quotations about:
overestimation
Note not all quotations have been tagged, so Search may find additional quotes on this topic.
People often overestimate what will happen in the next two years and underestimate what will happen in ten.
Bill Gates (b. 1955) American software magnate [William Henry Gates III]
The Road Ahead, “Afterword” (1996 ed.)
(Source)
First use of this specific formulation, but similar phrases can be traced back to the 1960s. More discussion of variations on this theme: People Tend To Overestimate What Can Be Done In One Year And To Underestimate What Can Be Done In Five Or Ten Years – Quote Investigator®.
