John Milton risks his security to call on Urania . . .

Urania
The Muses: Urania and Calliope (Detail)
Simon Vouet (ca. 1634)
Wikipedia

This post says nothing original, but despite my obtuseness, I finally understood a minor point in Milton's 'prayer' to the muse Urania in Paradise Lost 7.23-39, in which Milton describes himself as having returned to earth from his visionary, muse-inspired, enraptured heavenly journey, wherein he had described through the angel Raphael the dreadful war in heaven between the rebel angels and those angels remaining loyal to God, which safely past leaves Milton more safe again on earth . . . except that he's not entirely safe:

Standing on Earth, not rapt above the Pole,
More safe I Sing with mortal voice, unchang'd
To hoarce or mute, though fall'n on evil dayes, [ 25 ]
On evil dayes though fall'n, and evil tongues;
In darkness, and with dangers compast round,
And solitude; yet not alone, while thou
Visit'st my slumbers Nightly, or when Morn
Purples the East: still govern thou my Song, [ 30 ]
Urania, and fit audience find, though few.
But drive farr off the barbarous dissonance
Of Bacchus and his Revellers, the Race
Of that wilde Rout that tore the Thracian Bard
In Rhodope, where Woods and Rocks had Eares [ 35 ]
To rapture, till the savage clamor dround
Both Harp and Voice; nor could the Muse defend
Her Son. So fail not thou, who thee implores:
For thou art Heav'nlie, shee an empty dreame.

Thomas H. Luxon, ed. The Milton Reading Room, April 2012.

Milton is composing these lines -- or in his conceit, receiving them directly from the muse Urania herself! -- during "evil dayes" that have "fall'n on" him, by which he means the loss of political security with the fall of the Puritan Republic and the return of royalty and their supporters, whom Milton compares to those revellers drunk on the wine of Bacchus who mob-like tore Orpheus asunder in their drunken enthusiasm, because Milton fears for his own life at the hands of the royal revellers, though he also expects better protection from 'Urania' -- as he here calls the Holy Spirit -- than the mythical Orpheus received from his illusory muse.

Despite his spoken fears, Milton is rather bold to speak them here in a poem that he surely knows will be scoured for a political message and subject to prying, hostile eyes -- he must know that some one or other of those revellers will not be so blind as not to see his political point.

Or not?