[Greek letters must be pronounced with a long “E“ instead of an “I” sound]

I think that I shall never see
A letter lovely as a psi,
Which thrusts its base below the line
And lifts its pitchfork (ψ) for a sign

A psi that may at some times wear
A bar or tilde in its hair;
That bears exponents gracefully
And intimately lives with phi.

Psi’s can be writ by fools like me,
But only Greeks can make a xi.