Hilary of Poitiers
Catena Aurea · Matthäusevangelium 9
But when he saw the multitudes, he was moved with compassion on them, because they fainted, and were scattered abroad, as sheep having no shepherd. Then saith he unto his disciples, The harvest truly is plenteous, but the labourers are few; Pray ye therefore the Lord of the harvest, that he will send forth labourers into his harvest.
Figuratively; When salvation was given to the Gentiles, then all cities and towns were enlightened by the power and entrance of Christ, and escaped every former sickness and infirmity. The Lord pities the people troubled with the violence of the unclean Spirit, and sick under the burden of the Law, and having no shepherd at hand to bestow on them the guardianship of the Holy Spirit. But of that gift there was a most abundant fruit, whose plenty far exceeded the multitude of those that drank thereof; how many soever take of it, yet an inexhaustible supply remains; and because it is profitable that there should be many to minister it, He bids us ask the Lord of the harvest, that God would provide a supply of reapers for the ministration of that gift of the Holy Spirit which was made ready; for by prayer this gift is poured out upon us from God.