"In order that people may be happy in their work, these three things are needed: They must be fit for it: they must not do too much of it: and they must have a sense of success in it - not a doubtful sense, such as needs some testimony of others for its confirmation, but a sure sense, or rather knowledge, that so much work has been done well, and fruitfully done, whatever the world may say or think about it."

Next Quote

It is easy to obtain confirmations, or verifications, for nearly every theory-if we look for confirmations. Confirmations should count only if they are the result of risky predictions... A theory which is not refutable by any conceivable event is non-scientific. Irrefutability is not a virtue of a theory (as people often think) but a vice. Every genuine test of a theory is an attempt to falsify it, or refute it.

— Karl Popper