Some fell on rocky ground, and when it came up, the seedlings withered because they had no moisture.
The former paragraph began with an account of Christ's industry in preaching (Luk 8:1); this begins with an account of the people's industry in hearing, Luk 8:4. He went into every city, to preach; so they, one would think, should have contented themselves to hear him when he came to their own city (we know those that would); but there were those here that came...
Commenting on Luke 8:4-21
And some fell upon a rock,.... Which the other evangelists call "stony places", and "stony ground"; by which are meant such hearers whose hearts are, hardened through the deceitfulness of sin, and continue so notwithstanding the preaching of the word unto them.
Here we have the disciples' question, and our Saviour's reply: their inquiry is concerning the sense and signification of the parable, they own their ignorance, and desire better information. It is no shame for the best of ministers, yes, for the best of men, to acknowledge their own ignorance of the mysteries of religion; and to attend upon the means of instruction, in order to their farther information.