Return to Answer

More simply put, it appears that although the prepositional construction was present at the beginning, it shifted over time due to the bias of the general ear toward hear the -ing form as a progressive verb rather than as a noun (gerund).

More simply put, it appears that although the prepositional construction was present at the beginning, it shifted over time due to the bias of the general ear toward hearing the -ing form as a progressive verb rather than as a noun (gerund).

@Vitaly found an article that references some corroborative material. Here is an excerpt:

@Vitaly found an article ("American Speech", Duke University Press) that references some corroborative material. Here is an excerpt:

The American Heritage Dictionary seems to see this as stemming (hehe) from the Old English preposition on was placed in front of a verbal noun:

The American Heritage Dictionary seems to see this as stemming (hehe) from when the Old English preposition on was placed in front of a verbal noun: