John Calvin Commentary 2 Timothy 3:7

"ever learning, and never able to come to the knowledge of the truth." — 2 Timothy 3:7 (ASV)

Always learning, and yet they never can come to the knowledge of the truth. That fluctuation between various desires, of which he now speaks, occurs when, having nothing solid in themselves, they are tossed about in all directions. They “learn,” he says, like people who are influenced by curiosity and a restless mind, but in such a way that they never arrive at any certainty or truth.

It is ill-conducted study, and widely different from knowledge. And yet such persons think themselves prodigiously wise; but what they know is nothing, as long as they do not hold the truth, which is the foundation of all knowledge.