Paul McCartney once told a story about his relationship as a songwriter with John Lennon. If I remember it correctly, it concerned listening to a recording of the just-finished "Here, There and Everywhere" on a small tape deck in a hotel room during a tour of England. McCartney explained that they were both "northern lads" and therefore quite reserved (I guess you could say) in their words of praise for each other - not that there wasn't a great deal of appreciation and respect between them. Anyway, McCartney remembers Lennon saying, after listening to the song, "That's a good one, that one", which McCartney remembers as the biggest compliment Lennon ever paid one of his compositions.
Well, Lennon was right: it is a good one. The song features The Beatles in fine voice, with a splendid lead vocal from McCartney and inspired vocal backing from all of them. The introduction, marvelous and original, leads us into a tune that features both the keys of G major and G minor. The opening section is built on chords derived from the first steps (i.e. do, re, mi, fa) of the G major scale. With the lyric "wave of her hand" there is a shift to a minor sound (E minor). We are still essentially in the key of G, but a different chord within that key has become "tonicized" (i.e. become the new "do" of the moment - tonic is another word for do). This concept is crucial for a songwriter or listener to understand: basically, any chord can be of a passing nature or of a resting nature, and this song is an excellent one for hearing the difference. Then we have a shift to G minor (from G major) with the lyric "I want her everywhere" - which is known as a parallel shift, because the type of the chord has changed, but not the chord root. (The earlier change from G major to E minor is called a relative shift.) At the end of this G minor section the melody returns to major with the words, "But to love her is to need her everywhere", which I've always felt is one of the most sublime moments in all of popular music. No wonder John liked it.