Analysis of Lines

ON THE CELEBRATED PICTURE BY LEONARDO DA VINCI, CALLED THE VIRGIN OF THE ROCKS

While young John runs to greet
The greater Infant's feet,
The Mother standing by, with trembling passion
Of devout admiration,
Beholds the engaging mystic play, and pretty adoration;
Nor knows as yet the full event
Of those so low beginnings,
From whence we date our winnings,
But wonders at the intent
Of those new rites, and what that strange child-worship meant.
But at her side
An angel doth abide,
With such a perfect joy
As no dim doubts alloy,
An intuition,
A glory, an amenity,
Passing the dark condition
Of blind humanity,
As if he surely knew
All the blest wonders should ensue,
Or he had lately left the upper sphere,
And had read all the sovran schemes and divine riddles there.