The Greek verb speirō (σπείρω) means to sow seed, to scatter seed for cultivation, or figuratively to spread ideas or principles widely. It appears about 52 times in the New Testament and is the central verb in many of Jesus' agricultural parables. The imagery of sowing and reaping runs throughout the New Testament as a way of describing the Kingdom's growth and the moral law of spiritual cause and effect.
The Parable of the Sower (Matthew 13; Mark 4; Luke 8) is the foundational text for speirō — Jesus calls it the key to understanding all parables (Mark 4:13). The four soils represent four responses to the Word of God. Jesus Himself is the sower; the Word is the seed; the soils are human hearts. The same seed (same Word) produces dramatically different results depending on the condition of the heart. Paul extends this agricultural metaphor in 1 Corinthians 15:42–44 (the resurrection body is 'sown' in weakness, 'raised' in power) and Galatians 6:7–8: 'A man reaps what he sows (speirei)' — establishing the great law of spiritual sowing and harvest.