The well-known passage from Walt Whitman is a classical expression of this sporadic type of mystical experience.
"I believe in you, my Soul...
Loaf with me on the grass, loose the stop from your throat;...
Only the lull I like, the hum of your valved voice.
I mind how once we lay, such a transparent summer morning.
Swiftly arose and spread around me the peace and knowledge that pass all the argument of the earth,
And I know that the hand of God is the promise of my own,
And I know that the spirit of God is the brother of my own,
And that all the men ever born are also my brothers and the women my sisters and lovers,
And that a kelson of the creation is love." *
* Whitman in another place expresses in a quieter way what was probably with him a chronic mystical perception: "There is," he writes, "apart from mere intellect, in the make-up of every superior human identity, a wondrous something that realizes without argument, frequently without what is called education (though I think it the goal and apex of all education deserving the name), an intuition of the absolute balance, in time and space, of the whole of this multifariousness, this revel of fools, and incredible make-believe and general unsettledness, we call the world; a soul-sight of that divine clue and unseen thread which holds the whole congeries of things, all history and time, and all events, however trivial, however momentous, like a leashed dog in the hand of the hunter. [Of] such soul-sight and root-centre for the mind mere optimism explains only the surface." Whitman charges it against Carlyle that he lacked this perception. Specimen Days and Collect, Philadelphia, 1882, p. 174.