I believe to harvest is to plant the seeds of Gods word among people; it is in the parables that Jesus spoke. One of them is in chapter 20 of Matthew;
where the kingdom of heaven is 'likened' unto a householder (Christ) which went out early in the morning to hire (gather) laborers (christians) into his vineyard (world).
And he agreed with the laborers for a penny a day, and sent them into his vineyard.
And upon every hour, he found more laborers; standing idle in the marketplaces, and gave them the same agreement as the first.
Then all the laborers were called, and every man recieved a penny.
But those who had labored longer than the others, murmured against the goodman of the house, and felt that they should recieve more.
They complained that those servants wrought but one hour, and they have been made equal to us, who have borne the burden of the heat of the day!
So the householder said, friend, I did thee no wrong, is thine own eye evil, because I am good?
Didst thou not agree with me for a penny?
Many shall be called, few chosen.