This scene is from Mahabharata where Krishna is driving the rath and Arjuna is indulged in the war. During that time Krishna suggests him to stay calm and focus with all his heart on the war. We often get distracted by things that don't really matter and at times by those that matter but is out of our control. The four horses here represent different distractions that we have and like Krishna is directing the horses in the right direction to move forward. Reins of the horses is our mind we need to keep that in order to keep distractions at a minimum and move forward in life towards success.
