The anatomy of man is a key to the anatomy of the ape. (K Marx
The final goal is everything, the movement nothing. (Luxemburg
Keep Your Eye on the prize. (Civil Rights anthem
Assume a distribution which will make your hopeless contract possible(S. J. Simon in "Why You Lose at Bridge"; paraphrased from memory
vs. Group Two
The movement is everything, the final goal is nothing. (Bernstein
When the facts change, I change my mind. (Keynes
The art of politics is knowing what to do next. (James P. Cannon
Add a kopek to a ruble
One step at a time
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There are probably many other equivalents, especially in Group Two, but these are the ones that come quickly to mind.
Carrol