...Just to digress, but
"Although your mind's opaque.
Try thinking more if just for your own sake"
also from Rubber Soul of course, is among my favourite lines by anyone ever and it wasn't by Lennon OR McCartney.
But back to "I'm Looking Through You"...
One of the things I really love about RS is hearing John at his most McCartneyish; such twinkling melodies and gorgeous ballads, whilst enjoying Paul at his most Lennonesque, with waspish lyrics and honest exposure of inner feelings. They really influenced and brought out the best in each other on this album.
So we have Paul serving up this deliciously prickly number, delivering an accusatory slice of wounded emotions with a wonderfully pugnacious vocal. I wouldn't want to prolong the angst he was enduring through his rocky patch with Jane, but I do so wish he'd written more in this vein. He was capable of real bite and I can't be alone in relishing such a rare glimpse of Paul with his guard down: I think that people didn't get enough of spiky love songs, to coin a phrase.