To set himself in glory above his peers,
for the line would be ruined were the y to be omitted by a reader. The
extreme shortness of the two unaccented syllables, y and a, gives them
the quantity of one in the metre, and allows by the turn of voice a
suggestion of exuberance, heightening the force of the word glory. Three
lines lower Milton has no elision of the y before a vowel in the line,
Against the throne and monarchy of God.
Nor eight lines after that in the words day and night. There is elision
of y in the line,
That were an ignominy and shame beneath
This downfall.