You have an abbreviated understanding of the function of the two parts of the mind.
Without emotion, one would be driven not even to think.

As every thing is some material in some form, so too, reason and emotion. Emotion is the material difference, reason is the form applied to it.
As a table is not a table without a shape, or without the wood, neither is human psychology. Why do you think some of the most reasonable figures in history were the most passonate?