“No man is an island,' said John Donne. I feel we are all islands -- in a common sea.”

"Man, Androids and Machine" (1975), reprinted in The Shifting Realities of Philip K. Dick (1995) Lawrence Sutin, ed.
Context: These creatures are among us, although morphologically they do not differ from us; we must not posit a difference of essence, but a difference of behavior. In my science fiction I write about about them constantly. Sometimes they themselves do not know they are androids. Like Rachel Rosen, they can be pretty but somehow lack something; or, like Pris in We Can Build You, they can be absolutely born of a human womb and even design androids — the Abraham Lincoln one in that book — and themselves be without warmth; they then fall within the clinical entity "schizoid," which means lacking proper feeling. I am sure we mean the same thing here, with the emphasis on the word "thing." A human being without the proper empathy or feeling is the same as an android built so as to lack it, either by design or mistake. We mean, basically, someone who does not care about the fate which his fellow living creatures fall victim to; he stands detached, a spectator, acting out by his indifference John Donne's theorem that "No man is an island," but giving that theorem a twist: that which is a mental and a moral island is not a man.

Scientific American (1992), Vol. 267.

I Am a Rock
Song lyrics, Sounds of Silence (1966)
Source: Lyrics 1964-2008
Context: I am shielded in my armor
Hiding in my room safe within my womb
I touch no one and no one touches me.
I am a rock.
I am an island.
And a rock feels no pain.
And an island never cries.

Source: The Light That Failed

Song lyrics, Amarantine (2005)

Song lyrics, Islands (1987)

Variant: We live on a placid island of ignorance in the midst of black seas of the infinity, and it was not meant that we should voyage far.
Source: The Call of Cthulhu