Classic Poem

To make this clear. If we but once allow
(As most in present times admit) there dwells
'Twixt such and such a temperament (though how
Causation here doth operate quite repels
Man's finite guest) yet if the fact compels
Our credence, that a given cast of mind,
A given symmetry of form foretels,
Then must we grant, that, if two forms enshrined
Two kindred souls, they were to kindred forms assigned.