… is from page 14 of the 1948 printing of the second edition (1935) of Lionel Robbins’s classic 1932 tract, An Essay on the Nature & Significance of Economic Science:
Every act which involves time and scarce means for the achievement of one end involves the relinquishment of their use for the achievement of another.
DBx: The truth expressed here by Robbins is as indisputable as it is simple and important. But in practice this simple and important truth is often denied. Politicians make careers out of denying it – out of convincing voters that power invested in government can make 10-2=15.
But, obviously, no one can devote a scarce resource to the performance of X without causing the performance of Y or Z or both to decline. If more people consistently understood this reality, well over half of what governments do would not even be attempted.