“the terms good and evil are only applied relatively, so that the same thing may be called both good and bad according to the relations in view,”
Spinoza asks readers to examine evaluative terms in relation to purposes and comparisons instead of assuming that every judgment of good or bad names an absolute property.
Source details
On the Improvement of the Understanding, section 12, Project Gutenberg #1016 in R. H. M. Elwes's public-domain English translation. Spinoza says the terms good and evil are applied relatively while introducing his distinction between ordinary relative goods and the true/highest good sought by the unfinished treatise. It remains translation-mediated seventeenth-century methodological philosophy rather than a claim that all moral distinctions are meaningless.