Now it should be clear that the Buddhist doctrine of Kamma is very complex. Kamma simply means actions producing consequences, and it constitutes both wholesome (kusala) and unwholesome (akusala) consequences, depending on the wholesome or unwholesome nature of the actions. So most of the happiness and unhappiness that an individual experiences is partly or to a great extent, dependent on the moral quality of one’s actions.

Now it should also be clear that an individual’s Kamma also plays a major role in deciding one’s rebirth. As long as this Kammic force exits there is rebirth for beings are merely the visible manifestation of this invisible Kammic force.

Death is nothing but the temporary and of this temporary phenomenon. It is not the complete annihilation of this so called being. The organic life has ceased but the Kammic force which hither to actuated it has not been destroyed. As the Kammic force remains entirely undisturbed by the disintegration of the fleeting body, the passing away of the present dying thought moment only conditions a fresh consciousness in another birth.

It is Kamma, rooted in ignorance and craving that conditions rebirth. Past Kamma conditions the present birth and present Kamma, in combination with past Kamma conditions the future. The present id the offspring of the past and becomes in turn the parent of the future.

If we postulate a past, present and future life, there we are at once faced with the alleged mysterious problem. What is the ultimate origin of life?

Either there must be a beginning or there cannot be a beginning for life.

From the scientific standpoint, we are the direct products of the sperm and ovum cells provided by our parents. As such life precedes life with regard to the origin of the first protoplasm of life, scientists plead ignorance.

According to Buddhism, rebirth is explained as the combining of two factors namely consciousness (vinnana) and psycho-physical personality or what is simply called name and form (nama-rupa). Herein, name (nama) means the three aggregates i.e. feeling, perception and mental formations. And form or rupa means the physical form (body), sex and seat of consciousness.

This psycho physical personality is the foetus or the embryo in the mother’s womb. This becomes complete only when it is infused with consciousness, surviving from the past. This surviving consciousness is sometimes referred to as fonddhabba. This is nothing other then the "death consciousness" of a person or the last consciousness in his death bed which has turned into rebirth consciousness at the moment of obtaining rebirth.

The foetus formed by the union of mother and father, gets complete when it becomes infused with the rebirth consciousness of an individual who had passed away. The arising of name and form and consciousness takes place simultaneously and from that moment life begins to function.

In this rebirth consciousness that survives from the past are latent all the past impressions, characteristics and tendencies of that particular individual who foresee in samsara, going from birth to birth. Therefore, this consciousness, to a great extent determines the nature and character of the new personality. 

The connection between this surviving consciousness and the physical personality (name and form) is well emphasized in the Twelve-fold formula of Dependent Origination. It is explained that on mental formations or dispositions (sankhara) depend on consciousness and consciousness depends on psycho physical personality (nama-rupa).

This makes it clear that consciousness serves as a connecting link between two lives.

This life stream flows at infinitum, as long as it is fed by the muddy waters of ignorance and craving. This constant succession of birth and death in connection with each individual life flux constitutes what is technically known as samsara-recurrent wondering when the two are completely cut off, then only, if one so wishes, does the stream cease to flow, rebirth ends as in the case of the Buddhas and Arahants.

The Buddha is chiefly concerned with the problem of suffering and its destruction with this specific purpose in view, all irrelevant side issues are completely ignored.

How is one to believe that there is a past existence?

The most valuable evidence Buddhists cite in favour of rebirth is the Buddha, for He developed a knowledge which enables Him to read past and future lives.

Following His instructions, His disciples also developed this knowledge and were able to read their past lives to a great extent. Some great Indian Rishis were distinguished for such psychic powers as clairaudience, clairvoyance, thought-reading, remembering past births etc.

There are also some persons who due to their past Kamma, spontaneously develop the memories of their past births, and remember fragments of their previous lives.

In hypnotic states some relate experiences of their past lives, while a few others read past lives of others and even heal diseases.

Sometimes we get strong experiences which cannot be explained but by rebirth.

How often do we meet persons whom we have never met, and yet instinctively feel that they are quite familiar to us?

How often do we visit places, and yet feel impressed that we are perfectly acquainted with those surroundings? The Buddha tells us :-

"Through previous associations or present advantage, that old love springs up again like the lotus in the water."

It should be stated that this doctrine of rebirth can neither be proved nor disproved experimentally, but it is accepted as an evidently verifiable fact.

The cause of this Kamma, continues the Buddha, is ignorance of the Four Noble Truths. Ignorance is therefore the cause of birth and death.

In His first paean of joy (udana), the Buddha says :-

"Though many a birth wandered I, seeking the builder of this house, Sorrowful indeed is birth again and again." 

In the Dhammacakka Sutta, His very first discourse, the Buddha commenting on the second Noble Truth, states Yagam tanha ponobhabiku - this very craving which leads to rebirth. And that Buddha concludes that discourse with the words "Ayam ontima jati natthi doni ponobbhavo." This is my last birth. Now there is no more rebirth.