Kasina (Pali: कसिण kasiṇa; Sanskrit: कृत्स्न kṛtsna) refers to a class of basic visual objects of meditation used in Theravada Buddhism. The objects are described in the Pali Canon and summarized in the famous meditation treatise the Visuddhimagga.
The kasiṇa are typically described as a colored disk, with the particular color, properties, dimensions and medium often specified according to the type of kasiṇa. The earth kasiṇa, for instance, is a disk in a red-brown color formed by spreading earth or clay (or another medium producing similar color and texture) on a screen of canvas or another backing material.
Kasiṇa meditation is one of the most common types of samatha meditation, intended to settle the mind of the practitioner and create a foundation for further practices of meditation. In kasiṇa meditation, a mental object (kasina) is used as the object of meditation, being used to keep the mind focused whenever attention drifts.
The meditation treatise the Visuddhimagga is centered around kasina-meditation. According to American scholar monk Thanissaro Bhikkhu, "[t]he text then tries to fit all other meditation methods into the mold of kasina practice, so that they too give rise to countersigns, but even by its own admission, breath meditation does not fit well into the mold." He argues that by emphasizing kasina-meditation, the Visuddhimagga departs from the focus on dhyana in the Pali Canon. Thanissaro Bhikkhu states this indicates that what "jhana means in the commentaries is something quite different from what it means in the Canon."
According to scholars, the Visuddhimagga is one of the extremely rare texts within the enormous literatures of various forms of Jainism, Buddhism, and Hinduism to give explicit details about how spiritual masters were thought to actually manifest supernormal abilities. Abilities such as flying through the air, walking through solid obstructions, diving into the ground, walking on water and so forth are performed by changing one element, such as earth, into another element, such as air. The individual must master kasina meditation before this is possible. Dipa Ma, who trained via the Visuddhimagga, was said to demonstrate these abilities.
Although practice with kasiṇas is associated with the Theravāda tradition, it appears to have been more widely known among various Buddhist schools in India at one time. Asanga makes reference to kasiṇas in the Samāhitabhūmi section of his Yogācārabhūmi.