To tell the Beauty would decrease — Cross

To tell the Beauty would decrease 1
To state the Spell demean-
There is a syllable-less Sea
Of which it is the sign-
My will endeavors for its word 5
And fails, but entertains
A Rapture as of Legacies-
Of introspective Mines-
(F.1689/J.1700)
[1] the Beauty:: of the cross.
[3, 4] syllableless Sea, sign:: cross is a sign full of meaning.
[7] Legacies:: things left.
[8] Mines:: sources of wealthiness.