Sheila Davis, in her book The Craft of Lyric Writing, quotes John Hartford, who said he wrote "Gentle on My Mind" as a letter to someone, with "a lyric that went past your ear at a faster speed that was closer to speech."
Davis writes that "The lyric pulses like a chugging freight train. Its incessant TUM-ta-ta-ta, TUM-ta-ta-ta, TUM-ta-ta-ta carries us across the wheat fields and highways and rivers of a wanderer whose recurring vision of an ever-waiting lover gives him the only roots he knows." p. 239.
Hartford "touches all our senses as he subtly changes from a long-distance lens to a closeup of the singer in the final verse. We see this traveling man in a changing landscape... In the third stanza we get a glimpse of the man himself, still a vague figure in the distance walking along a railroad track. In the last verse, however, he comes so close that we could reach out and touch his stubbly beard and dirty hat. Finally, as we watch him drink some steaming soup, we feel what his cupped hands 'round a tin can' are feeling. Hartford's images are so immediate, so tactile, we almost become the man. That's using imagery to its fullest." p. 155
Yeah, Glen Campbell was a superb talent. Great guitarist, fantastic singer. I loved his early stuff, mostly the Jimmy Webb stuff: "Phoenix," "Wichita Lineman," and "Galveston". So much so, I even learned them on guitar. RIP, Glen.