The Buddha once explained how the feelings we have can be classified in many ways, and how we can have as many as 108 kinds of feelings, as follows…
2 feelings: Bodily and mental feelings
3 feelings: Pleasant, painful and neither-painful-nor-pleasant feelings
5 feelings: Feelings of pleasure, pain, gladness, sadness and equanimity
6 feelings: 6 feelings from the senses of eye, ear, nose, tongue, body and mind
18 feelings: 6 feelings above in terms of 3 feelings each of gladness, sadness and equanimity (6 x 3)
36 feelings: 18 feelings above in terms of the 2 ways of life – lay and renounced (18 x 2)
108 feelings: 36 feelings above in terms of 3 feelings each of past, present and future (36 x 3)
So long that we are not free from dissatisfaction due to the presence or absence of the 108 feelings above, we can be said to have as many as 108 defilements which lead to afflictions.
This is a reason why there are 108 beads on Buddhist prayer beads (malas). Each time a bead is moved during chanting, it symbolises conquering of each of the 108 defilements. Though this is seldom the actual case in practice, it does remind us of the goal of working towards mindful transcendence of all our defilements.
Related Article:
Atthasatapariyaya Sutta
http://www.accesstoinsight.org/tipitaka/sn/sn36/sn36.022.nypo.html