The expression “beside myself” dates all the way back to the birth of Modern English, and has typically been used to explain that someone is not in their right mind. French became the language of the upper class in Britain after William conquered England in 1066. It remained that way even during much of the 100 Years War between England and France (1337-1450s). In the Middle English period (around 1100-1500), books were scarce because they had to be hand-copied, and were mostly written in French or Latin. As the English grew more angry with the French, they desired to establish English as the language of the common people throughout the entire country. The first attempt at accomplishing such a task was to start printing books in English. Not only for the students at prestigious universities like Oxford and Cambridge, but for the general population as well.
William Caxton, born in 1422 and passing away in 1492, learned the art of printing in Cologne, France. In 1476, Mr. Caxton established the first English printing press at Westminster while translating The Recuyell of the Histories of Troye from French to English. With the emergence of the printing press, he immediately began printing original English works such as The Canterbury Tales in an effort to rapidly spread the English language. In the work titled “Arthur”, dedicated to King Henry VII’s son, Caxton translated the French phrase, “hors de soi”. The phrase directly translates to “outside herself”, but he translated it to “mad & beside herself”. The expression was used in reference to Dido’s anger and disposition when she found out about Aeneas’ departure. This marked the first time the expression was used in print. Substituting the word “beside” for “outside” was perfectly appropriate at that particular point in time.
Beside” was used in phrases to mean “out of a mental state or condition, as ‘beside one’s patience, one’s gravity, one’s wits” (according to the Oxford English Dictionary), which started in the 15th century and carried its way through the 19th century. It is not very practical to substitute these two words in today’s age anymore. The first time it was recorded this way was in the English Wycliffte Sermons in the 1370s. Currently, to be besides one’s self can be translated or understood to mean that a person is acting in an extreme of any emotion, whether it be fear, joy, anger, etc. Mr. William Caxton is widely credited for bringing English to England and helping usher in the Modern English era.