In Luke 8:14, Jesus gave a parable about four different types of soils. The four types of soils represent four kinds of hearts and there is a hidden key in each one. The third kind of soil is the thorny soil. The reason there is thorny soil is because there are weeds. The thorny soil is soil of the soul. Once a person becomes saved his spirit is reborn not his soul. Once the spirit is reborn it cannot sin. The way we weed the garden of our heart is by getting our soul saved. It is a spiritual progress.