6 ideas
Sprezzatura is a studied nonchalance that hides the labor behind an accomplishment, so skill appears to arise naturally. Observers who sense ease infer a reserve of ability greater than what is shown, which makes the concealment of effort worth more than the display of it.
Visible striving, the effort to impress or to be seen trying, ruins even real excellence, because it shows that the performer needs the audience's approval. Grace comes from avoiding affectation 'as a rough and dangerous reef', and people discount any merit that looks forced.
The courtier's primary profession is arms, but martial skill without letters produces a crude man who cannot record, justify, or dignify his deeds. Learning gives action its meaning and memory, and action gives learning its purpose, so the ideal combines both rather than choosing one.
Grace, skill, and charm are not ends in themselves; they are instruments for winning a prince's trust and favor. With that trust the courtier can tell the ruler unwelcome truths and steer him toward virtue. Polish that never gets converted into honest counsel is mere vanity.
No behavior is graceful in itself. The same jest, display, or skill succeeds or fails depending on who is present, the setting, and one's rank and age. Discretion, the continuous reading of the audience and occasion, is therefore the master skill that governs all the others.
The lover ascends from a single body to universal beauty and finally to the divine, moved by contemplation instead of possession. This lets an aging courtier love without folly, because the desire is redirected rather than suppressed.