The 'Chinese' Theory: For and Against

[Mauro]

But buying a printed copy or copying the Chinese characters would be pointless, since he would not have been able to read anything.  To get a translation he would need a local doctor who spoke Latin or his language, which would be practically impossible. 

But he knew and understood the spoken language, by definition. Why did he not make and write down a translation himself? I bet it's much easier than devise an ex-novo tonal phonetic notation. And more useful too.