One who does not understand the four material elements is no true ascetic.At Sāvatthī. “Mendicants, there are these four elements. What four? The elements of earth, water, fire, and air. There are ascetics and brahmins who don’t truly understand these four elements’ origin, ending, gratification, drawback, and escape … There are ascetics and brahmins who do truly understand these four elements’ origin, ending, gratification, drawback, and escape …”