Claim: There are four Tetrads, the establishment or arousing of mindfulness, which also has four Ānāpānasati each.
Evidence: These are divided into four tetrads (i.e., sets or groups of four). Ānāpānasati (Pali; Sanskrit ānāpānasmṛti), meaning "mindfulness of breathing" ("sati" means mindfulness; "ānāpāna" refers to inhalation and exhalation), is a form of Buddhist meditation originally taught by Gautama Buddha in several suttas including the Ānāpānasati Sutta. First Tetrad 1. Breathing long (Knowing Breath) 2. Breathing short (Knowing Breath) 3. Experiencing the whole body 4. Tranquillising the bodily activities Second Tetrad 5. Experiencing rapture 6. Experiencing bliss 7. Experiencing mental activities 8. Tranquillising mental activities Third Tetrad 10. Gladdening the mind 9. Experiencing the mind 11. Centering the mind in samadhi 12. Releasing the mind Fourth Tetrad 13. Contemplating impermanence 16. Contemplating relinquishment 15. Contemplating cessation 14. Contemplating fading of lust