Wonderment, It helps to understand that the brain was developed by the body. In other words it has an evolutionary history and developed from the inside out. Our emotion centure is called the limbic system and in development is the reptilian part of the brain, otherwise known as the R complex. So it is the older more elemental part of our brain.
It is more often than not pulling the strings of emotivation, only part of the time guided/ advised by rational understaning. Alexander Pope said best I think, "The passions/ read emotions are the elements of life/desire, the passions fill the sails, and only sometimes the course is set with reason, but no wind, we are not going anywhere.