What does he will reap what he sows mean?

However bad may be the harvest that is reaped by each individual, as a consequence of the life he has led upon earth, he has the whole of eternity before him during which to sow well and reap the richest of rich harvests. It may take time and great effort—it may cost the individual much mental anguish—there may be overwhelming remorse, but the soul will have, and does have, every aid and opportunity to regain whatever ground he has lost, and so rise to the greatest heights in spiritual advancement.

—Robert Hugh Benson in Spirit