Theories for truths, fable for fact;
system for science vex the thought
Life's one great lesson you despise--
to know that all we know is nought.

This is in fact:--

Well didst thou say, Athena's noblest son,
The most we know is nothing can be known.

The next is:--

Essence and substance, sequence, cause,
beginning, ending, space and time,
These be the toys of manhood's mind,
at once ridiculous and sublime.

He is not the only one who so regards "bothering Time and Space."
A late definition of the "infinitely great," viz., that the idea
arises from denying form to any figure; of the "infinitely
small," from refusing magnitude to any figure, is a fair specimen
of the "dismal science"--metaphysics.

Another omitted stanza reads:--

How canst thou, Phenomen! pretend
the Noumenon to mete and span?
Say which were easier probed and proved,
Absolute Being or mortal man?