To have another language is to possess a second soul.
? Charlemagne (742/7 ? 814), King of the Franks

Multilingualism is the natural potential available to every normal human being rather than an unusual exception: ?Given the appropriate environment, two languages are as normal as two lungs? (Cook 2002:23).

It need not even require the ability to speak two unrelated languages; a user of e.g. the ?literary? and a vernacular/dialectal variety is already multicompetent, with today only ?a handful of isolated pockets of ?pure? monolinguals, now hard to find even in the mountains of Papua New Guinea? (ibid.). At the same time, multicompetence does not require perfect fluency in all the languages at one?s command; thus, setting the boundary would probably be a mission impossible.

The advantages that multilinguals exhibit over monolinguals are not restricted to linguistic knowledge only, but extend outside the area of language. The substantial long-lived cognitive, social, personal, academic, and professional benefits of enrichment bilingual contexts have been well documented. Children and older persons learning foreign languages have been demonstrated to:

• have a keener awareness and sharper perception of language. Foreign language learning ?enhances children?s understanding of how language itself works and their ability to manipulate language in the service of thinking and problem solving? (Cummins 1981);
• be more capable of separating meaning from form;
• learn more rapidly in their native language (L1), e.g. to read, as well as display improved performance in other basic L1 skills, regardless of race, gender, or academic level;
• be more efficient communicators in the L1;
• be consistently better able to deal with distractions, which may help offset age-related declines in mental dexterity;
• develop a markedly better language proficiency in, sensitivity to, and understanding of their mother tongue;
• develop a greater vocabulary size over age, including that in their L1;
• have a better ear for listening and sharper memories;
• be better language learners in institutionalized learning contexts because of more developed language-learning capacities owing to the more complex linguistic knowledge and higher language awareness;
• have increased ability to apply more reading strategies effectively due to their greater experience in language learning and reading in two?or more?different languages;
• develop not only better verbal, but also spatial abilities;
• parcel up and categorize meanings in different ways;
• display generally greater cognitive flexibility, better problem solving and higher-order thinking skills;
• ?a person who speaks multiple languages has a stereoscopic vision of the world from two or more perspectives, enabling them to be more flexible in their thinking, learn reading more easily. Multilinguals, therefore, are not restricted to a single world-view, but also have a better understanding that other outlooks are possible. Indeed, this has always been seen as one of the main educational advantages of language teaching? (Cook 2001);
• multilinguals can expand their personal horizons and?being simultaneously insiders and outsiders?see their own culture from a new perspective not available to monoglots, enabling the comparison, contrast, and understanding of cultural concepts;
• be better problem-solvers gaining multiple perspectives on issues at hand;
• have improved critical thinking abilities;
• better understand and appreciate people of other countries, thereby lessening racism, xenophobia, and intolerance, as the learning of a new language usually brings with it a revelation of a new culture;
• learn further languages more quickly and efficiently than their hitherto monolingual peers;
• to say nothing of the social and employment advantages of being bilingual ? offering the student the ability to communicate with people s/he would otherwise not have the chance to interact with, and increasing job opportunities in many careers.

Thus, just like Latin once used to be taught as an academic exercise, mental gymnastics with the aim of cognitive training, it has been demonstrated that people who know more than one language usually think more flexibly than monolinguals. Many celebrated bilingual writers?such as John Milton, Vladimir Nabokov, Samuel Barclay Beckett, or Iosif Brodsky?attest that knowing a second language enhances the use of the first.