Sowing and Reaping
The gospels use the idea of sowing and reaping as a metaphor for evangelism and conversion. By its nature, this is from the perspective of the Lord or the one doing outreach, not the perspective of the one being reached.

This metaphor is closely related to the ideas of preaching, hearing and believing, which will be seen more clearly in the comments below.
 
Section Text Comments
40,41 JN 4:36 "Already he who reaps is receiving wages, and is gathering fruit for life eternal; that he who sows and he who reaps may rejoice together. [37] "For in this case the saying is true, `One sows, and another reaps.' [38] "I sent you to reap that for which you have not labored; others have labored, and you have entered into their labor."

JN 4:39 And from that city many of the Samaritans believed in Him because of the word of the woman who testified, "He told me all the things that I have done." [40] So when the Samaritans came to Him, they were asking Him to stay with them; and He stayed there two days. [41] And many more believed because of His word; [42] and they were saying to the woman, "It is no longer because of what you said that we believe, for we have heard for ourselves and know that this One is indeed the Savior of the world."

The context of this passage is the new faith of the Samaritans, precipitated by the visit of Jesus with the woman at the well. 

Sowing is seen as a necessary predecessor to reaping. The point of Jesus' marks is that the harvest of these Samaritans is the end result of much past spiritual labor by others. 

83 MT 13:18 "Hear then the parable of the sower. [19] "When anyone hears the word of the kingdom, and does not understand it, the evil one comes and snatches away what has been sown in his heart. This is the one on whom seed was sown beside the road. [20] "And the one on whom seed was sown on the rocky places, this is the man who hears the word, and immediately receives it with joy; [21] yet he has no firm root in himself, but is only temporary, and when affliction or persecution arises because of the word, immediately he falls away. [22] "And the one on whom seed was sown among the thorns, this is the man who hears the word, and the worry of the world, and the deceitfulness of riches choke the word, and it becomes unfruitful. [23] "And the one on whom seed was sown on the good soil, this is the man who hears the word and understands it; who indeed bears fruit, and brings forth, some a hundredfold, some sixty, and some thirty."

MK 4:20 "And those are the ones on whom seed was sown on the good soil; and they hear the word and accept it, and bear fruit, thirty, sixty, and a hundredfold."

LK 8:15 "And the seed in the good soil, these are the ones who have heard the word in an honest and good heart, and hold it fast, and bear fruit with perseverance.

The parable of the soils shows how the preached word bears fruit. Jesus illustrates four different "soil types." 

When sown to the disinterested person, there is no result at all. "Does not understand" doesn't have to do with intelligence or capacity but with spiritual interest and perception of the heart; the same term for understanding (Greek suneimi) is used in Mt 13:13,14,15-- and 13:23 to describing the fourth soil.

When sown to the shallow person, rapid but short-lived growth results. This person eventually falls away.

When sown to the preoccupied individual, limited growth results. This person's growth is stunted.

When the word is accompanied by acceptance, understanding, a good heart and perseverance, the desired result follows. The word truly affects this person.

What does this parable teach us about Christian conversion? First, the "won soul" comes from the word; the sower is merely an agent. Second, the growth depends upon the person who hears the word, not the one sowing. Third, it takes time to determine the ultimate response. Fourth, different people bear a different amount of "fruit." The fourth soil's "thirty, sixty or a hundredfold" are all accepted but obviously quite different in end result. (In context, the "fruit" that is borne is not future people converted but simply the spiritual health of individual.)

84 MK 4:26 And He was saying, "The kingdom of God is like a man who casts seed upon the soil; [27] and goes to bed at night and gets up by day, and the seed sprouts up and grows--how, he himself does not know. [28] "The soil produces crops by itself; first the blade, then the head, then the mature grain in the head. [29] "But when the crop permits, he immediately puts in the sickle, because the harvest has come." While the sower sows, the seed grows in its stages apart from his further effort or understanding. Yet, the harvest comes in due time.

Concerning Christian conversion, we may observe that the word produces the growth on its own, without the effort or understanding of the sower. Then when the crop permits, the harvest comes immediately. This suggests bringing people to the point of conversion as soon as their response permits.

98,
139
MT 9:35 And Jesus was going about all the cities and the villages, teaching in their synagogues, and proclaiming the gospel of the kingdom, and healing every kind of disease and every kind of sickness. [36] And seeing the multitudes, He felt compassion for them, because they were distressed and downcast like sheep without a shepherd. [37] Then He said to His disciples, "The harvest is plentiful, but the workers are few. [38] "Therefore beseech the Lord of the harvest to send out workers into His harvest."

LK 10:2 And He was saying to them, "The harvest is plentiful, but the laborers are few; therefore beseech the Lord of the harvest to send out laborers into His harvest. 

A great harvest requires many workers. There also seems to be some connection between the needs of people (distressed, downcast, uncared for) and the size of the harvest.
219 JN 15:16 "You did not choose Me, but I chose you, and appointed you, that you should go and bear fruit, and that your fruit should remain, that whatever you ask of the Father in My name, He may give to you.  Jesus' desire for the apostles was "remaining fruit." This seems to be in contrast to fruit that will not last, perhaps the old covenant of Moses. This would suggest the church itself is in view as the "fruit that will last," the end result of the apostle's ministry (ref. Mt 16:18)

Copyright © 2002 John Engler. All rights reserved.
Scripture Taken from the NEW AMERICAN STANDARD BIBLE, Copyright © 1960- 1995 by the Lockman Foundation.