Who is in the picture behind every Carlos Santana concerts?

I have been in at least three Santana concerts and have seen just as many concert videos. And, on every single one I notice the picture of a bearded man in the background. Who is this man? Is he the head of a religious group, a Guru, or political figure?|||Probably Caesar Chavez, but I'd have to have my memory refreshed. I can't find a pic. There's also that radical that Obama likes but I can't think of his name...but it's probably Chavez.