13 Lines on Smallness, from Lucretius

How small can anything be? We know of creatures
So tiny they would seem to disappear
If they were less than half their present size.
How big do you suppose their livers are?
Their hearts? The pupils of their eyes? Their toes?
Pretty minute, you must admit. Well, then,
What about things like those atomic motes
That form the elements of mind and spirit?
Diminutive, to say the least. Nor can we
Find with our finger tips the cause of smell
That clings there from the touch of marigold,
Centaury, heal-all, wormwood, southernwood.
So images move beyond our powers of sight.