Rational people agree in nature and desire good for others
Formal Statement
Insofar as men live in obedience to reason, they always necessarily agree in nature. The highest good of those who follow virtue is common to all. The good which every man who follows virtue desires for himself, he will also desire for other men.
In Plain Language
Freedom is social, not solitary. When people act from reason rather than from confused passions, they converge: they want the same thing (understanding), and that thing is not a scarce resource. Your knowledge does not diminish mine — it enhances it. Conflict arises from passive affects and scarcity, not from reason. This is why Spinoza insists that the free man is not a hermit but a citizen. The more rational people there are around you, the more your own power is augmented.
Why This Follows
Step 14 (df-14) identified the highest good as knowledge of God, which is an adequate idea. This step draws the social consequence: because adequate ideas are common notions — structural truths that hold for all — people guided by reason share the same good. Freedom is inherently communal because its content (understanding) is inherently shareable.
Freedom is social: rational agents agree in nature and share the highest good.
Is Spinoza being naive about human cooperation, or does the distinction between passionate conflict and rational agreement point to something real in your experience?