" The physical heart, which houses the spiritual heart, beats about 100,000 times a day, pumping two gallons of blood per minute and over 100 gallons per hour. If one were to attempt to carry 100 gallons of water (whose density is lighter than blood) from one place to another, it would be an exhausting task. Yet the human heart does this every hour of every day for an entire lifetime without respite. The vascular system transporting life-giving blood is over 60,000 miles long—more than two times the circumference of the earth. So when we conceive of our blood being pumped throughout our bodies, know that this means that it travels through 60,000 miles of a closed vascular system that connects all the parts of the body—all the vital organs and living tissues—to this incredible heart. "

― Hamza Yusuf , Purification of the Heart: Signs, Symptoms and Cures of the Spiritual Diseases of the Heart