One is the unit and two is a plural. Somewhat like zero, I have my axial language, the Japanese language, as I'm a native Japanese speaker. If I had only one language as my foreign language to study, the additional language is overwhelming. It's ... the relation of face-to-face, or just the relation of inside/outside. The contrast of zero and one. When facing it, you've got nowhere else to turn to. But adding even one more language to study, there emerges something different. It's something like ... a party. A set of [0, 1, 2]. If you're a native Japanese speaker and studying English and, say, Latin, it's a party of the three: three languages there. The perspective changes into something somewhat different. Or perhaps it's like finding yourself in a companionship consisting of the three. The relationships between the three will bring a richer level in perspectival complexity than two, probably.