6th April, 1966 - Wednesday. Beginning of Revolver sessions.

Recording 'Mark I' (working title of `Tomorrow Never Knows')(takes 1-3). Studio 3. Abbey Road. "John showed up with a song after we'd had a couple of days off. I remember being in Brian Epstein's house in Chapel Street in Belgravia. We met up and John had a song that was all on the chord of C, which in our minds was a perfectly good idea. I was wondering how George Martin was going to take it, because it was a radical departure; we'd always had at least three chords, and maybe a change for the middle eight. Suddenly this was John just strumming on C rather earnestly - 'Lay down your mind...' And the words were all very deep and meaningful - certainly not 'Thank You Girl'; a bit of a change from all that.
George Martin took it very well. He said, 'Rather interesting, John. Jolly interesting!' So we got in and recorded it as a fairly straightforward rock'n'roll band thing." - Paul, from The Beatles Anthology.