Jeremiah 1:6 Meaning Then I Said

Whatever a person declares himself to be sets a harder limit than any skill he lacks.

A claim about ability can be tested by the end of the week. A claim about identity settles the matter permanently, because nobody goes out collecting evidence against his own definition of himself, and the attempt that would produce that evidence is precisely what the definition forbids.

Youth was a fact, and a fact hardens into a fence the moment it is accepted as the limit of what can be attempted. Yahweh does not argue the fluency. He reaches past the skill to the identity, hands over the words, and sends him anyway, because the fence had to move before the feet would. Anyone waiting to feel qualified before speaking is still waiting when the work goes to someone else.