The Boston Symphony’s new maestro Andris Nelsons is a boisterous young athlete in an old man’s job – one of the rising 30-somethings in front of the great orchestras of the world. And still he seems younger than that and more different than we expected — almost childlike, when he’s reaching out with an open-arm hug for the sound he wants from his players. The look could be early Jack Nicholson, but the back story as we’re hearing it in his green room is boyhood in Latvia, as the Soviet era came apart 25 years ago. It matters that he was tuned musically between empires: Tchaikovsky and Shostakovich on the Russian side, Wagner, Strauss and Mahler to the West in Germany. It turns out that Maestro Nelsons talks the way he plays: emotionally unguarded, with big-spirited ideas about where great music comes from, and how it connects with us. Backstage he is telling us — with grand gestures, some singing, much laughter — about some of the “thousand voices” in his head before a performance.

Of course these theological / philosophical / ‘to be or not to be’ questions are of course among the thousand. They are saying: ‘you are not a good guy’ or ‘you can’t do anything; it’s too early for you to conduct this piece, or that piece.’ Those voices are there all the time, but then they’re saying: ‘you must perform this piece — Tchaikovsky 6 or The Rite of Spring — and you can’t produce it in just a professional way.’ It’s saying: ‘you have to be emotionally involved with all your professionality and your personality as well.’

In The Rite of Spring, there is a lot of this orthodox, mystical, natural, wild thing. In Stravinsky I couldn’t call it religious in the sense of Christianity, but of course there is a search for explanation, trying to find what it is, what the world means… I think even Stravinsky is maybe not flirting but coquetting when he says it’s not emotional. It is what’s inside the human soul. When it’s over, I feel energized… You feel energized from the earth, but also you want to take a shower…

Of course I am like a big child, and I hope to stay like that. Music expresses our inside world, and for me as a conductor, to have a chemistry with the musicians is extremely important. If we perform and we are not on the same ship emotionally, I don’t believe we can perform any piece honestly or very well… In this close human familiar feeling consists our humanity. And love, in a way. I love my musicians, and I respect them. I encourage them not be shy, to show their emotions. Of course it goes together with knowledge, experience, professionality and a tradition, you know. It is not only spontaneous feeling. But how can you perform “Tristan” if you don’t love. For example, loving my family. It all comes through the small things. It’s like chamber music, and then it can spread. It all starts with your family, and if you experience that you can share and love in a wider range. Sometimes I think it is easier to invent an airplane than to experience real love, for example. And it is actually worth much more to raise a child as a good person than to invent an airplane.