When friendship disappears then there is a space left open to that awful loneliness of the outside world which is like the cold space between the planets. It is an air in which men perish utterly.

Belloc frames friendship not as a pleasant accessory but as a vital human atmosphere. When it vanishes, the individual is exposed to an impersonal “outside world” figured as interplanetary cold—vast, indifferent, and lethal. The metaphor suggests that social life is what makes existence habitable: friendship provides warmth, meaning, and a sense of belonging that shields a person from isolation and despair. The line also implies a moral warning: modern life’s pressures, pride, or ideological divisions can erode friendship, and the resulting loneliness is not merely sad but spiritually and psychologically destructive—an environment in which people can “perish” inwardly even while outwardly surviving.