One friend in a life-time is much; two are many; three are hardly possible. Friendship needs a certain parallelism of life, a community of thought, a rivalry of aim.

Adams argues that deep friendship is rare not because people are scarce, but because true intimacy requires sustained alignment: similar life trajectories (“parallelism of life”), shared intellectual premises (“community of thought”), and even a productive competitiveness (“rivalry of aim”) that keeps both parties engaged and growing. The arithmetic—one is “much,” two are “many,” three “hardly possible”—suggests that the conditions for profound friendship are demanding and hard to maintain across multiple relationships at once. Implicitly, Adams distinguishes acquaintanceship from friendship: the latter is a long-term, mutually shaping bond that depends on congruent values and ambitions rather than mere affection or proximity.