Mahathera Ledi Sayadaw - Abhidhamma.com

93. citta
94. utu
95. ahara
Kamma means moral and immoral actions committed in previous existences.
Citta means mind and mental concomitants existing in the present life.
Utu means the two states of Tejo-dhatu, the fire-element, i.e., heat (unha-tejo) and cold (sita-tejo).
Ahara means the two kinds of nutritive essence, internal nutriment that obtains from the time of
conception and external nutriment that exists in edible food.
Out of the twenty-eight species of material qualities, the nine species, i.e., the six bases, two
sexes, and life, are produced only by Kamma. The two media of communications are produced
only by Citta.
Sound is produced by Citta and Utu. The three plasticities are produced by Citta, Utu, and Ahara.
Of the remaining thirteen, excluding Jarata (decay) and Aniccata (impermanence), the eleven--
comprising the Four Great Essentials, nutriment, visible form, odour, savour, the element of
space, integration, and continuance are produced by the four causes. These eleven always
appertain severally to the four classes of phenomena produced by the four causes. There are no
phenomena that enter into composition without these. Material phenomena enter into composition
with these, forming groups of eight, nine, and so forth, and each group is called Rupa-Kalapa.
As to the two salient features, decay and impermanence, they exclude themselves from the
material qualities born of the four causes as they disorganise what has been produced.
CAUSES OR ORIGINS
Of these eighty-two ultimate things Nibbana, inasmuch as it lies outside the scope of birth (Jati),
does not not need any originator for its arising; neither does it need any cause for its maintenance
since it also does not come within the range of decay and death (Jara-Marana). Hence Nibbana is
unconditioned and unorganized. But, with the exception of Nibbana, the eighty-one phenomena,
both mental and material, being within the spheres of birth, decay and death, are conditioned and
organized things.
Among the four causes already dealt with in connection with the material qualities, Kamma is
merely an originator and Citta (mind) is simply a stimulus. The physical body develops, stands,
and is maintained by the power of the warmth element called Utu and by the power of the essence
of nutriment. If the forces of the latter two come to an end, the forces of the former two also can
no longer operate but cease simultaneously.
In the case of trees, for example, the seeds are only their origins. They grow, develop, and are
maintained by means of the elements of earth and water. If these two principles fail them, the
power of the seed also fails along with them. Here the physical body is like the tree; Kamma is
like the seed; the warmth-element, or what is called Utu is like the earth; the nutritive essence is
like the rain-water, which falls regularly at proper seasons; and mind is like the atmosphere and
the heat of the sun, both of which give support from outside.
With regard to the causes of mind and mental properties, three things are needed for the arising of
Resultants; a past kamma, a basis to depend upon, and an object. The first is like the seed of the
tree, the basis is like the earth, and the object is like the rain- water.