Merleau-Ponty & Lawrence de Arabia / a puzzle for bilingual phenomenologists

This is passage from M-P’s Phenomenology of Perception that I keep turning around in my head:

“Hence the full meaning of a language is never translatable into another. We may speak several languages, but one of them always remains the one in which we live. In order completely to assimilate a language, it would be necessary to make the world which it expresses one’s own, and one never does belong to two worlds at once.” (The translation by Colin Smith comes from the Routledge Classics 2002 edition, p. 218)

M-P provides an interesting footnote as evidence to support his claim. By no one else but D. E. Lawrence:

‘In my case, the effort for these years to live in the dress of Arabs, and to imitate their mental foundation, quitted me of my English self, and let me look at the West and its conventions with new eyes: they destroyed it all for me. At the same time I could not sincerely take on the Arab skin: it was an affectation only. Easily was a man made an infidel, but hardly might he be converted to another faith. I had dropped one form and not taken on the other, and was become like Mohammed’s coffin in our legend. . . . Such detachment came at times to a man exhausted by prolonged physical effort and isolation. His body pledded on mechanically, while his reasonable mind left him, and from with- out looked down critically on him, wondering what that futile lumber did and why. Sometimes these selves would converse in the void; and then madness was very near, as I believe it would be near the man who could see things through the veils at once of two customs, two educations, two environments.’ (T. E. Lawrence, The Seven Pillars of Wisdom, Jonathan Cape, pp. 31–2.)

I wonder how could this fit with Kleist’s idea that language comes by as we speak…