. . . and let me ride.
Comparative Poetics (c.f. the essential treatise by Calvert Watkins, How to Kill a Dragon, 1995) teaches us that as phrases in a poetic tradition evolve, they can change syntactically / phonetically while semantics remain intact or change semantically while syntactic / phonetic structure remains intact. The increased speed of communication and frequency of exposure to poetic artifacts in the age of mass communication has both sped up the evolutionary change of such phrases and provided us with resources of heretofor unknown richness for studying such change. Furthermore, due to the advent of audio recording, we finally possess resources for examining such change in melodies and musical rhythms.
Consider, for example, the phrases / melodies "Swing low, sweet chariot" and "Swing down chariot stop." Both "originate" in early 20th century gospel (by no means the start of their history! ~ though the imagery is (at least) traceable to the stories of Elijah and Ezekial (following Thomas Mann's strategy, we may even wish to posit a connection of sorts between these themselves)).
We can trace "swing down (sweet) chariot stop," for example, from gospel, through funk, to rap:
Herman Stevens Singers, Swing Down Chariot
Parliament / Funkadelic, Swing Down
Dr. Dre, Let Me Ride
Arguably, while the syntactic / phonetic structure of the phrase has remained largely the same (only the adjective "sweet" has been added, possibly due to assonance with "swing low sweet chariot"), the melody altered only slightly (though the rhythm and tempo being changed considerably), the semantics of the phrase has changed. At least, there is a strong implication in the Parliament performance that the "chariot" is literally a spaceship / cosmic chariot, metaphorically signifying (most likely) the vehicle of some kind of artistic / political / sexual liberation. Even if we take the chariot in biblical tales to be metaphorical for a route of communication with the divine, both the literal and metaphorical roles of the word "chariot" have changed. By the time Dr. Dre gets a hold of it, the phrase seems to literally reference joy riding in Cadillacs, while metaphorically hold little weight.
Furthermore, even if surface structure has remained, one wonders whether the underlying syntactic structure has changed - "Swing down chariot, stop, and let me ride" vs. "Swing (on) down (by the) chariot stop, and let me ride" - changing not just the references of the terms, but even their semantic relationships.
Contrast this with a phonetic change with (arguably) no (or little) semantic change (at least on the metaphorical level):
Dizzy Gilespie, Swing Low, Sweet Cadillac
An abbreviated live version
Here, although the word "chariot" has been replaced with "cadillac," the remaining lyrics are a commentary on communication with the divine in much the same spirit of the original gospel version (though admittedly differing in perspective). Thus, the metaphorical meaning has remained unchanged which the surface expression has changed.
Even if this is an accurate analysis of the phenomenon, however, it seems clear that the subtlety of meaning involved in each case prevents any simplistic arguments that the semantics has changed or not. Even in the Dr. Dre version, there remains a lingering sense of spiritual transition in the chorus; even if highly metaphorical, this slight "color" is somehow inherited from the phrase's original sense, and lingers like a stain on any reimagining of the same.