Charles Ellicott Commentary Luke 8:6

"And other fell on the rock; and as soon as it grew, it withered away, because it had no moisture." — Luke 8:6 (ASV)

Upon a rock.—Better, upon the rock. Note here also the use of a more accurate word than the “stony (or rocky) ground” of the other two reports, and the statement that it withered because it lacked moisture. This is obviously not without its force in the spiritual interpretation of the parable, the “moisture” being the dew and rain of God’s grace, without which the seed could not put forth its roots. This represents one aspect of what was lacking, as the having no depth of earth represents another.