In my opinion, seedtime and harvest is the grand-daddy of all principles. The the cookie-cutter principle into which all other principles fit.
With Proverbs 13:18, we learn that even the honor we receive is the result of the seed that we sow.
Seed: ". . . he who regards a rebuke"
Harvest: "will be honored".
Luke 6:38 is a principle that governs how to receive from God.
Seed: "Give"
Harvest: "and it shall be given to to you good measure, pressed down, shaken together shall men give into your bosom . . ."
In James 4:7, God informs us on how to turn away our adversary. That he runs from us is only the result of seed sown
Seed: "Resist the devil"
Harvest: "and He will flee from you."
James 4:8 is a principle that governs your relationship with God, but it is an emulation of seedtime and harvest.
Seed: "Draw nigh to God"
Harvest: "and He will draw nigh to you . . ."
Galatians 5:16 is a principle that governs subjecting your flesh.
Seed: "Walk in the Spirit"
Harvest: "and you shall not fulfill the lust of the flesh."
Cause and effect, give and take, bartering, supply and demand . . . All are reflections of seedtime and harvest.
In my opinion, seedtime and harvest is the chief among principles that govern. And regardless of whether or not we recognize it, our very existence is submitted to this principle: "While the earth remains, seedtime and harvest . . . shall not cease."
All you say and do is seed sown. For your good or your bad, this principle is always in operation. The only question is what you're sowing.
