I'll give you 86 Billion Reasons Why...
When we take a deep dive into our brains function and capabilities, it's a quite intimidating venture.
With approximately 86 BILLION neurons in our brain it is the same number of the stars in the Milky Way.
If you dig deeper and want to investigate the "connections" these neurons make with one another, called Synapses, the numbers then get mind boggling.
Take a look at this very interesting video that gives a great starting point into the inner workings of our brains and how we've gotten to this point in history.
AXONS (Sciatic nerve is an example of the longest Axons in the body)