People have raga dwesha (hate and obsession) on every issues. it is this raga dwesha that leads to samsaara again and again . If you are obsessed with something , you yearn for it, you struggle hard to gain it, no struggle goes in vain . So you come back to gain the fruits of your obsession. Similarly when you hate something, you nurture dislike and revenge on it. You struggle to achieve revenge, hence you come back to revenge ,avenge and dislike. thus raga and dwesha are single most important factors governing cause and effect. If one gets rid of this raga and dwesha , one attains state of vairagya.