“It is not what he has, nor even what he does, which directly expresses the worth of a man, but what he is.”

“all appears to change when we change”

“Uncertainty is the refuge of hope.”

“The stationary condition is the beginning of the end”

“A belief is not true because it is useful”

“To know how to suggest is the art of teaching.”

“The land of easy mathematics where he who works adds up and he who retires subtracts.”

“At the age of 45, most days in Tucson were spent feeling like I was on the summit of Mauna Kea, as I was exhibiting debilitating health symptoms that corresponded to what I saw at very high altitud...”

“The hour is only long thus, if you've waited.”