It's a well known fact that "Spirituality is Universal", and once in a while when we come across a literary classic such as William Blake's "Auguries of Innocence", it supplements our belief with much more vigour.
"To see a world in a grain of sand,
And a heaven in a wild flower,
Hold infinity in the palm of your hand,
And eternity in an hour."
Looks like William Blake was indeed influenced by Hindu literature. This excerpt appears to have some influences from the following Bhagavad-Gita verses. A fairly large contingent of his critics, who have insisted that there was a relationship between Blake's work and Hindu mythology, appear to be on the right track!
As stated in our sacred Bhagavad-Gita: BhG VII.25
naham prakasah sarvasya
yoga-maya-samavrtah
mudho yam nabhijanati
loko mam ajam avyayam
which translates to:
na - nor, aham - I, prakasah - menifest, sarvasya - to everyone, yogmaya - internal potency, samavrtah - covered, mudhah - foolish, ayam -these, na - not, abhijanati - can understand, lokah - people, mam - Me, ajam - not born , avyayam - limitless/infinite.
Can be interpreted as follows:
I am not visible to everyone since I am covered , concealed and enveloped by my yogmaya, my internal power, my strength. Unintelligent and foolish are those who cannot understand me. People, I am the unborn, limitless, infinite, the eternal.
In order to experience the existence of God within us, we need to set the judgmental social perspectives aside, attain purity and innocence of a child's mind. Only a child's heart within us can "see a world in a grain of sand".
Further, as emphasized in BhG XV.11:
arjuna uvaca
pasyami devams tava deva dehe
sarvams tatha bhuta-visesa-sanghan
brahmanam isam kamalasana-stham
rsims ca sarvan uragams ca divyan
which translates to:
arjunah uvaca--Arjuna said; pasyami--I see; devan--all the demigods; tava--Your; deva--O Lord; dehe--in the body; sarvam--all; tatha--also; bhuta--living entities; visesa-sanghan--specifically assembled; brahmanam--Lord Brahma; isam--Lord Siva; kamala-asana-stham--sitting on the lotus flower; rsin--great sages; ca--also; sarvan--all; uragan--serpents; ca--also; divyan--divine.
Can be interpreted as follows:
Arjun says to Lord Krishna that he sees all the demigods, living entities, even Lord Brahma, and Lord Shiva seated on the lotus flower, many sages and divine serpents, all assembled together in his body. Arjun could see the infinity, the eternity , just by sitting in one place, all by the grace of Lord Krishna, since he had set aside all his judgments and accepted life as it is.
The bottom line is, no matter, what faith you believe in, or whichever religion you follow, the ultimate goal always comes down to be "the attainment of and oneness with Eternal Being".