Passion or commitment?

Working in a creative industry that is largely transient, there is very little loyalty. I don't know what it's like to be given "long service leave", and I never will. The longest period I've held a job for is 2 years. But I do understand what it is to be passionate about the type of work you do, and how important it is to stay committed. But which is more important in determining long-term success?

Some people think that passion is the cornerstone of creating a truly happy and successful career. But the way I see it, you can be passionate about a thousand different things at the same time - a religion, a hobby, a person, an ideal - but you can only really be 100% committed to a few things at the same time. Plus passion is flighty, depending wholly on an emotional connection.... but commitment? Commitment requires steadfast dedication regardless of emotions, ideals or a changing landscape. You are either committed or you're not.

My father once told me that marriage is the same way. "It's the commitment part that's most important", he'd say. I'm not the right person to make an educated guess about commitment vs passion in a long-term relationship, but I do know this one thing: I've always approached love from a passion perspective, and I'm still single.