Mother Teresa identifies something psychological that mere loneliness cannot capture—the particular ache of invisibility, of mattering so little to anyone that your presence makes no dent in the world. Most of us fear being forgotten *after* we've mattered; she's naming the deeper dread of never mattering at all. When a colleague never remembers your name despite seeing you weekly, or when your text goes unanswered for months, that small erasure starts to feel like proof of your own insignificance. The insight cuts because it exposes how our sense of self isn't built internally but confirmed through the eyes of others—we become real through being known.