There are few things wholly evil or wholly good. Almost everything, especially of government policy, is an inseparable compound of the two, so that our best judgement of the preponderance between them is continually demanded.

The remark expresses a pragmatic, anti-absolutist view of political decision-making: most real-world choices—particularly in public policy—mix benefits and harms rather than fitting neatly into moral categories. Lincoln (as the attribution has it) urges continual, disciplined judgment about which side “preponderates,” implying that responsible governance requires weighing tradeoffs, unintended consequences, and competing goods. The emphasis on “continually demanded” suggests that such evaluation is not a one-time act but an ongoing civic and statesmanlike duty, resisting ideological certainty and encouraging humility in political argument.