Albert Barnes Commentary Acts 18:19

"And they came to Ephesus, and he left them there: but he himself entered into the synagogue, and reasoned with the Jews." — Acts 18:19 (ASV)

And he came to Ephesus. This was a celebrated city in Ionia, in Asia Minor, about forty miles south of Smyrna. It was chiefly famous for the temple of Diana, usually considered one of the seven wonders of the world. Pliny calls this city the ornament of Asia. During Roman times, it was the metropolis of Asia.

This city is now under the dominion of the Turks and is almost in a state of ruin. Dr. Chandler, in his travels in Asia Minor, says—"The inhabitants are a few Greek peasants, living in extreme wretchedness, dependence, and insensibility; the representatives of an illustrious people, and inhabiting the wreck of their greatness; some in the foundations of the glorious buildings which they raised; some beneath the vaults of the stadium, once the crowded scene of their diversions; and some in the tombs which received their ashes"—Travels, p. 131, Oxford, 1775.

According to Josephus, the Jews were very numerous in Ephesus and had obtained the privilege of citizenship.

Left them there. This refers to Aquila and Priscilla (Acts 18:24–26).

Reasoned with the Jews. (The word "reasoned" here can also be rendered "discoursed.") See the comments on Acts 17:2.