When I was a child. — The natural childhood and manhood of this life are analogous to the spiritual childhood of this life and the spiritual manhood of the life to come.
I understood as a child, I thought as a child. — The first word expresses mere simple apprehension, the second word implies active intellectual exertion. It has been suggested that the three words here used refer back respectively to the gifts previously mentioned. “I spoke” corresponds to the “tongues,” “understood” to the “prophecy,” and “I reasoned” to the “knowledge.” Without intending any such very definite correspondence of these three expressions, the Apostle probably naturally made the points of analogy correspond in number with what they were intended to illustrate.
But when I became a man. — Better, but now that I have become a man I have given up the ways of a child. The point brought out is his present state as a man, and not, as the English version might seem to imply, some fixed point of transition in his past history. The contrast he seeks to make clear is between two states of life.