Steve Jobs explains the importance of both thinking and doing

“The doers are the major thinkers. The people who really create the things that change this industry are both the thinker-doer in one person.”

This is applicable outside of tech too, and he uses Leonardo DaVinci as an example:

“Did Leonardo have a guy off to the side that was thinking five years into the future about what he would paint or the technology he would use to paint it? Of course not. Leonardo was the artist, but he also mixed his own paints. He also was a fairly good chemist and knew about pigments and human anatomy. Combining all of those skills together—the art and the science, the thinking and the doing—is what resulted in the exceptional result… There is no difference in our industry. The people that have really made the contributions have been the thinkers and the doers.”

Jobs speculates that one of the reasons people mix this up is because it’s easy to take credit for the thinking:

“It’s very easy for someone to say ‘I thought of this three years ago.’ But usually when you dig a little deeper you find that the people who really did it were also the people who worked through the hard intellectual problems.”