The idea that we use only one language for all that we do is completely foreign to me. I was born in the late 1960s in Berkeley, California, into a family that was Spanish speaking. I spent the majority of my childhood and adolescence ping-ponging between Mexico and the United States. Summers and the holiday seasons were spent with extended family in Mexico. When I was in the ninth grade, my parents sent me to study for a year in Mexico. It was full immersion for a whole year. This immersion led to full literacy as my Spanish skills erupted as I took all my classes in a language that I had always spoken but rarely read.

 

            As I came back to the United States to finish high school and then spent the first two years of college in the United States, I settled back into schooling in English. Since I had spoken both languages since I was young, to me it felt like both had a symbiotic relationship. I had navigated both of them in clearly defined contexts, one used in Mexico, the other in the United States.

 

            I also grew up in a household filled with music. My mother’s family had always loved music. My mother and many of my uncles had pursued music with passion. I fell right in line. As a child, I loved all kinds of different artists. My musical interests ranged from Mexican rancheras and boleros up to Earth, Wind & Fire, Johnny Cash, and later in the 1980s, REO Speedwagon, Journey, and the Gap Band. Even pop music today has its allure. More recently, one group that has captured my imagination is Maroon 5 and its lead singer Adam Levine.

 

            The allure of music also had unintended consequences. My dad had introduced me to Brazilian music when I was young. I grew to love it so much that it led me to want to study in Brazil for my year abroad. When I got to UC Berkeley, the week before I started my first year, I went to the Education Abroad Office. I looked at the exchange program in Brazil and read about São Paulo, Brazil’s economic capital. I imagined that it would be like a Portuguese-speaking Mexico City, noisy, full of traffic, teeming with life, and full of music.

 

            In my first year of college, I began taking Portuguese classes. At first, I had a pretty thick accent, and my understanding of Portuguese was limited. I remember that my classmates could actually speak and understand what the professor was saying. Many had outright conversations and would do their homework by talking in Portuguese. I felt like I was behind everyone. Across semesters, I kept making progress but could not catch up to my classmates.

 

            Because I knew Spanish and had taken some Portuguese, I met the prerequisites for studying abroad in Brazil. I boarded the plane and landed ten hours later in a completely different land. It was July, warm in Los Angeles, where I had taken off. São Paulo was in the middle of winter, and the cold chilled me to the bone. The city I thought would be like Mexico City felt different. Bigger and noisier. And my Portuguese was good but slow and halting.

 

            Then came an experience like no other I had ever had. Being immersed in Portuguese was like putting a sledgehammer to my language system. As a two-year-old, I had been exposed to Farsi for a year in home care. Even though my mom said I spoke to my caretaker, that language just kind of came and went. I was so young I have no memory of knowing Farsi. Spanish had grown stronger as it built on all my experiences during the summers I spent in Mexico. And my year in ninth grade. However, arriving in Brazil and being immersed in Portuguese was completely different.

 

            Portuguese tried to take over. Before I knew it, I could not say simple words in Spanish, and my English kept getting worse and worse. I ended up spending two years there, one in the exchange program and a second in a gap year that I took before completing college. During this time my proficiency in Portuguese got so good that I could pass for a native speaker.

 

            Sounding like a native in Portuguese came at a price. When I came back to the United States at age twenty-two, everyone kept wondering what had happened to my English. My Spanish had also taken a hit. My grandmother said I had lost my beautiful Mexican accent and I spoke muy raro. Reading in English was slow and effortful.

 

            By the time I finished college two years later, I had finally regained my English skills, and my Spanish had recovered. The rest of my twenties ended up being a period of language stability. Portuguese was kept around by the few times I could use it with friends or people I would meet and the songs I would occasionally sing aloud. I pretty much thought that I would remain trilingual for the rest of my life.

 

            My language stability changed in my mid-thirties when I was invited to spend time at the Max Planck Institute in Leipzig, Germany. Going to Germany was disorienting. My mismatch with the language context in Leipzig became most apparent to me one night when I decided to hail a taxi. As I got in, I searched desperately for any way to communicate with the driver. I asked, “English?” The driver responded, “Nein, Russisch.”

 

            The former East Germany as part of the Soviet bloc taught its children Russian as a second language. The taxi driver and I spoke at least five languages between the two of us. But none of them in common. I handed the driver a small piece of paper with an address, he nodded, and then we drove off. As we wound through the streets, I could not help but notice the billboards. Since English and German share most of the alphabet, I could read all the words that zoomed by as we sped through the city. But it looked funny to me at that time. There were a lot of k’s, and some vowels had dots above them. I had no idea what all of it meant. I remember staring up at one particular billboard on a building and thinking, “This language is incomprehensible. There is no way I will ever learn to speak, read, or write it.”

 

            As was the case when I studied Portuguese, in my German classes I again felt that everyone spoke better than I did. I spent years working on my vocabulary, practicing aloud in my car, reading magazines for German adult learners, and I even went back to spend a year, and later I went for three consecutive summers. After seven years of classes, one year, and three summers, I still felt like I could not do anything spontaneously.

 

            In 2015, fourteen years after my first visit, I was able to go back for a year and take my family with me on another research visit. The first three months of that visit were a tongue-tied form of torture. My speech was halting and slow. Group conversations were impossible. The thoughts would come in floods, but the words rolled off my tongue like mud slithering down a slide. Trips to any non-German–speaking country invariably led to all kinds of electrical cobwebs ganging up against my growing ability in German.

 

            Suddenly, six months in, my German got much better. When people asked why my German was so good, I would reply, “Ich habe gelittet.” I have suffered. That is the only way to describe what it was like to learn German. It was hard, with lots of ups and downs, and even today with all that work and time it is less than perfect. Then a German would invariably quote Mark Twain: “Life is too short to learn German.”

 

            During my life, I have been exposed to six different languages and gained fluency in four of them. Each of these language-learning episodes has taught me how flexible our language system is. They have taught me how the ways in which we learn change with age but also how they seem to pile up on top of one another. My Farsi might be seemingly gone, but it has to have played a role in giving me the flexibility needed to learn more than one language. My Portuguese eventually became accentless, and my German accent is very light, relatively speaking. It is almost as if all the cobwebs and back-and-forth of having to pry open my language system over time strengthened my language muscles.

 

            All these experiences eventually led me to actually study how the brain adapts to learning more than one language. In writing my first book, The Bilingual Brain, I realized that learning new languages doesn’t just tell us about language learning. Learning new languages also tells us about how we learn.

 

            My work and my own experiences had yielded insights into this process of learning in general. We take what we know, we tweak it a bit, we try again, we tweak again, and so on and so forth. At times we show sudden improvement and then sudden loss. What I have come to realize is that language that in the words of Elizabeth Bates is “a new machine built out of old parts” is true of most higher-level skills that we acquire.

 

            In The Bilingual Brain, I talk about languages like species in an ecosystem: at times they fight for resources, other times they cooperate, and over time they become symbiotic. As I learned more languages, each language shifted and adapted as the others came in. With all these languages in my head, my English became better in my thirties and forties, not in spite of the other languages I learned, but because of all those other languages. In my work, I have come to think about English, the language that I know the best, as having pieces of German, Spanish, and Portuguese that are sewn together.

 

            Mastery grows naturally from my previous book. The main idea is that all the things that we marvel at as humans—language, reading, and even competitive sports—involve the combination and recombination of smaller pieces that become a greater whole. Language learning, in my mind, works as an analogy for the way in which we learn complex skills.  

 

            My childhood was not just filled with learning languages. I also did a lot of other things. Earlier I mentioned my love for music. I also loved to play sports with my friends, either in the schoolyard or in my neighborhood.

 

            As a kid one of my favorite sports was basketball. But I never got past five feet seven, and my basketball “career” ended on the playground in middle school. I never made it far in soccer or football. That left baseball as the only game in which I played on an actual team in junior high. Hitting a baseball allowed me to discover that I had very good hand-eye coordination, which was aided by exceptional eyesight.

 

            As I grew older, I left the schoolyard and team sports behind and took up the sport played by my family in Mexico, tennis. In tennis, I took all the sports I had learned as a child and combined them into one: throwing and catching from baseball, shooting, passing, and footwork from basketball, and throwing a football have become a collage that today I call tennis. It is as if this new sport is a chimera in which one sport is a combination of different pieces of each sport that are stitched together. The way I think about it, learning a complex skill like tennis is like learning a language. We layer together all these different experiences to create a greater whole.

 

            The process of learning something new or becoming better at something we already know applies to everyone. Whether we are a professional in a sport, a polyglot who speaks at least eleven languages, or just learning something new and becoming good at it, the same rules apply. No matter what our ultimate level of expertise, we as humans are adept at taking a bunch of little pieces and creating a much bigger whole. Our gift as humans—our defining feature—is the emergent process that leads to mastery.