Full Idea
The centre of a circle is directly opposite any designated point on the circumference. In this way, whatever is in any part of time coexists with what is eternal as being present to it even though past or future with respect to another part of time.
Gist of Idea
Eternity coexists with passing time, as the centre of a circle coexists with its circumference
Source
Thomas Aquinas (Summa Contra Gentiles [1268], I.66), quoted by Robin Le Poidevin - Past, Present and Future of Debate about Tense 2 c
Book Reference
'Questions of Time and Tense', ed/tr. Le Poidevin,R [OUP 2002], p.27
A Reaction
A nice example of a really cool analogy which almost gets you to accept something which is actually completely incomprehensible.