Jamieson, Fausset and Brown on Acts 16:14-15

14-15. Lydia--a common name among the Greeks and Romans.

a seller of purple, of the city of Thyatira--on the confines of Lydia and Phrygia. The Lydians, particularly the inhabitants of Thyatira, were celebrated for their dyeing, in which they inherited the reputation of the Tyrians. Inscriptions to this effect, yet remaining, confirm the accuracy of our historian. This woman appears to have been in good circumstances, having an establishment at Philippi large enough to accommodate the missionary party (Ac 16:15), and receiving her goods from her native town.

which worshipped God--that is, was a proselyte to the Jewish faith, and as such present at this meeting.

whose heart the Lord opened--that is, the Lord Jesus (see Ac 16:15; and compare Lu 24:45; Mt 11:27).

that she attended to the things ... spoken by Paul--"showing that the inclination of the heart towards the truth originates not in the will of man. The first disposition to turn to the Gospel is a work of grace" [Olshausen]. Observe here the place assigned to "giving attention" or "heed" to the truth--that species of attention which consists in having the whole mind engrossed with it, and in apprehending and drinking it in, in its vital and saving character.