While the Buddha understood the mind to be a `flow' or `stream' of mental events (vi¤¤ànasota), later abhidhamma thinkers speculated that it was actually a string of individual thought moments (cittavãthi) arising and passing away at great rapidity. Later still, the theory developed that the last thought moment (cuticitta) a person has before they die will determine their next life. This idea, now current in Theravàda, seems to be an unjustified development of the Buddha's teachings and at odds with his idea of kamma and the efficacy of morality.

The theory of the importance of the last thought moment is not mentioned in any of the Buddha's discourses or even in the later Abhidhamma Piñaka. The Tipiñaka records many occasions where the Buddha counselled people who were either dying or critically ill. If the last thought is really crucial to one's destiny one would expect such occasions to be the most appropriate time for him to mention it, and yet he never did. Nor did he mention it anywhere else. Mahànàma once confided to the Buddha his anxiety about dying at a time when his mind was distressed and confused, thinking it might result in him having a negitive rebirth. The Buddha reassured him that because he had developed faith, virtue, learning, renunciation and wisdom for a long time, he had nothing to fear if such a thing should happen (S.V,369).

The theory of the importance of the supposed last thought moment first appears in an undeveloped form in the Milindapa¤ha(aprox. 1st century CE) which says: `If someone did unskilful things for a hundred years but at the time of death was mindful for one moment of the Buddha, he would be reborn amongst the gods' (Mil.80). By the time the Visuddhimagga was composed, this apocryphal idea had been worked out in detail and had come to be considered orthodox (Vism.458-60). Apart from not having been taught by the Buddha, there are several philosophical, ethical and logical problems with the theory that the last thought moment is the deciding factor in one's circumstances in the next life.

If a person had lived a relatively good life but in the anxiety and confusion just preceding their death they have some negative thoughts they would, according to this theory, have a bad rebirth. Likewise, one could have lived an immoral and dissolute life but pass away with ease and in peace and, therefore, have an advantageous rebirth. This negates the whole idea of kamma, the teaching that the sum total of our intentional thoughts, speech and actions conditions our future, both in this life and the next. Further, it is very difficult to understand how just one or two thought moments, each of them supposedly a millisecond long (khaõa), can cancel out perhaps many years of good or evil thoughts, speech and actions. This theory also fails to take into account causation. If everything is conditioned, and the Buddha taught that it is, then the last thought moment must be conditioned by the second last thought moment which in turn must be conditioned by the third last thought moment, etc. This means what we are thinking, saying and doing right now will have an impact on what is in our minds at the time we die. Therefore, to emphasise the last thought moment is to give exaggerated significance to the effect and neglect the cause, i.e. how one is living here and now.

The theory of the last thought moment does not fit well with other things the Buddha taught. For example, he said (A.II,80) that trying to work out the subtle and interconnected workings of kamma (kammavipàka) would send one mad (ummàda). And yet the Visuddhimagga describes in extraordinarily minute detail what supposedly happens in the mind just before death, the past kamma that makes it happen and the kammic consequences it will have in the next life. The Buddha's comment that thinking about the intricacies of kamma can cause madness should also make us very cautious of the Visuddhimagga's theorizing.

The descriptions of the mind contained in the Abhidhamma Piñaka and its commentaries are sometimes helpful and certainly very sophisticated, considering the period in which they were written. However, they are also speculative, sometimes overly mechanistic and simplistic and occasionally downright wrong. This being so, it is important to distinguish between what the Buddha taught and the ideas that developed from his teachings in the succeeding centuries. See Unthinkables