Tomorrow is another day


question: Could you please tell the origin,meaning and usage of "After all, tomorrow is another day!"

"Gone with the Wind". Book by Margaret Mitchell 1936, movie 1939.
Life goes on. Even if it's a mess, you can always try again tomorrow. RRC

Only today counts; tommow is unreal until it becomes today. Possible source...
LUKE Ch 12
27: Consider the lilies how they grow: they toil not, they spin not; and yet I say unto you, that Solomon in all his glory was not arrayed like one of these.
28: If then God so clothe the grass, which is to day in the field, and to morrow is cast into the oven; how much more will he clothe you, O ye of little faith?