Full Idea
A thing can be self-evident in either of two ways: on the one hand, self-evident in itself, though not to us; on the other hand, self-evident in itself, and to us.
Gist of Idea
Some things are self-evident to us; others are only self-evident in themselves
Source
Thomas Aquinas (Summa Theologicae [1265], Art 1, Obj 3)
Book Reference
'The Existence of God', ed/tr. Hick,John [Macmillan 1964], p.32
A Reaction
A clear distinction, which is hard to deny, though there are lots of borderline cases. Self-evident to genius, and self-evident to future genius. Self-evident to almost everyone. Goldbach's Conjecture may be self-evident but unknowable.