&gt; Is is quite rare (I can only think of one occasion in my life), where I have listened to an articulate and intellectual communicator &#x2F; speaker, who was not monolingual in whatever language they were speaking.<p>This has been my experience, too.<p>In my case, I speak two languages every day, and have done so for decades. I often say or write things that are syntactically incorrect in both languages. If I pay attention, I can correct them, but it does affect my fluid production of speech. Correct grammar rules have become a blurry mess, and I hate that.