Touched my mouth; literally, caused (his hand) to touch my mouth. Jeremiah had said that he was unskilled in oratory; the Divine answer is that the words which he has to speak are not his own, but those of Jehovah. Two things are obvious:
1. The touching of the lips is not purely metaphorical, as in Psalms 51:15 (comp. Psalms 40:6); it represents a real experience.
2. This experience, however, can only have been a visionary one, analogous to that vouchsafed to Isaiah at the opening of his prophetic ministry. In the grand account given by Isaiah of his inaugural vision (which has evidently influenced the form of the vision of Jeremiah), we read of the same significant act on the part of one of the seraphim. It is the same act, certainly, but it symbolizes, not as here the communication of a prophetic message (comp. Matthew 10:19), but the purification of the lips. Does it not seem as if Isaiah had attained a deeper insight into the spiritual regeneration needed by the prophet than had been granted to Jeremiah? Another point in which Jeremiah's account seems inferior to that of Isaiah is plastic power. Notice how Jeremiah dwells upon the meaning of the words; this is a reflective element which diminishes the poetic power of the narrative. A word may Be added to explain that "visionary" is not here used in opposition to "based on fact." That the two epithets are susceptible of combination is well shown in the vision described by Pere Gratry, in his 'Souvenirs do ma Jeunesse', the reality of which is not in the least impaired in the writer's mind by its thoroughly inward character: "Dens teutes ces seines interieures, je n'imaginais rien … c'etaient de saisissantes et tres-energiques realites auxquelles je ne m'attendais nullement."