E-mails are dispatches without the physical form of mail. Somewhat analogously, e-motions are dispatches or signals without the physical motion, and in fact emotions are often coupled with actual motion (fear->fight or flight, happiness->smiling, anger->violence, etc.). As the brain processes get more and more decoupled from motion, those processes are less emotional and more what we think of as thoughts. Even these thoughts are generally coupled, at least loosely, with emotion and sometimes motion.
When I look at the numerous theories (all unproven) of how the brain is fundamentally structured, I personally find the analogy of the brain being the muscle of thought the most compelling:
...that cognition is a phylogenetic outgrowth of movement and that cognition utilizes the same neural circuitry that was originally developed for movement.From this point of view, intelligence in thinking is little different than intelligence in controlling motion. In other words, it's the ability to coordinate the actions of different muscles groups, but in this case, without the muscles.
Movement relies on the deliberate, smooth, properly sequenced and coordinated, graded, contractions of selected ensembles of discrete muscles. Therefore, the neural circuitry of movement was specialized for this purpose. Soon, a new design possibility emerged: the elaborate neuronal machinery of movement control could be applied to brain tissue itself. In particular, discrete brain structures, modules, emerged that could be controlled exactly like individual muscles. ... By manipulating these modules in properly coordinated 'movements' (thought processes), valuable information processing (cognition) could be carried out – thereby further enhancing animal competitive success and diversity.