I have never considered myself a linguist since.

From Trying to Please by John Julius Norwich.  Page 203. 

My biggest failure was with Arabic. My early fascination with languages still continued, and—wrongly as I was all too soon to discover—I considered myself a pretty good linguist. My French had been fluent since I was six, I had a goodish working knowledge of German and Italian, and a degree from Oxford in Russian; more recently, I had been an interpreter in Serbo-Croat. Why should Arabic hold any terrors? I managed to get permission for an initial ten days of intensive tuition at MECAS—the Middle East Center for Arab Studies—which was run by the Foreign Office in the village of Shemlan, forty minutes or so up the mountain. This was intended primarily for professional Arabists who were to spend most of their active life in the Middle East. The full course lasted some eighteen months, but I felt that those ten days would be enough to give me a push-off, after which two or three hours’ study a week would do the rest.

How wrong I was. Now for the first time I came face to face with a seriously difficult language—a language whose words, roots, and sentence structure were totally unlike anything I had come across before; whose plural nouns were apparently unrelated to their singulars; whose cursive, right-to-left script not only reduced many letters to one or two dots above or below their neighbors, but normally left out all the short vowels, so that effectively you had to know what a word was before you could read it. After a few months, still barely able to ask for the butter, I gave up. I consoled myself as best I could with the reflection that most of my Lebanese friends were themselves far happier in English or French, some of them indeed speaking Arabic not very much better than I could myself; still, it had been a salutary lesson. I have never considered myself a linguist since.