Jamieson, Fausset & Brown

How knoweth . . . letters--learning (Act 26:24). having never learned--at any rabbinical school, as Paul under Gamaliel. These rulers knew well enough that He had not studied under any human teacher--an important admission against ancient and modern attempts to trace our Lord's wisdom to human sources [MEYER]. Probably His teaching on this occasion was expository, manifesting that unrivalled faculty and depth which in the Sermon on the Mount had excited the astonishment of all.