I've heard it claimed Galileo said or wrote:
All truths are easy to understand once they are discovered. The point is to discover them.
Where did he say this?
Dialogo sopra i due massimi sistemi del mondo (1632), Day two:
SAGR. Tali [facili da intendersi] sono tutte le cose vere, doppo che son trovete; ma il punto sta nel saperle trovare.
[Stilmann Drake transl., p.225] So [easy to understand] are all truths, once they are discovered; the point is in being able to discover them.
[ Th.Salusbury transl.,209] So are all truths, when once they are found out, but the difficulty lyeth in finding them.