Q: Where do thoughts come from?
A: All thoughts come from ignorance, from holding to the duality of self and other, from defilements, from unvirtuous actions, and from the four main obscurations. All these are gathered in the apparition of the thought.
If the mind were not empty then the thoughts appearing in it would not be empty either – something would remain, as with this pile of oranges; there would be a pile of past thoughts and a pile of future thoughts. But unlike these oranges, past thoughts do not remain anywhere nor do future thoughts have any existence – they are empty; they appear from emptiness and disappear back into emptiness. If it were not so, if something substantial remained from the many thoughts we have had since birth, our bodies could never contain them all. All these thoughts can arise in the mind because it is unobstructed. We have learned many things at school, but where are all those things now? If thoughts were not empty, then it would be as if you had a bag full of them and you could reach in and pick one out. The Buddha taught that the mind, which is empty, has no birth, no place, and no obstruction. It is void, like a mirror, and all karma, good or bad, is like a form appearing in the mirror.
Kalu Rimpoche – Dharma Teachings Vol I (p296)
Dharma Teachings – Given at Samdrup Darjay Ling – Sonada, Summer, 1973 By the Very Venerable Kalu Rinpoche
Biblioteca I Kalu Rimpoche – Kalu Rimpoche – Dharma Teachings Vol I
Centro Budista Tibetano Kagyü Pende Gyamtso – Brazil