"A being is nothing but a combination of  physical and mental forces or energies. What we call death is the total non-functioning of the physical body. Do all these forces and energies stop altogether with the non-functioning  of the body? Buddhism says 'No'. Will, volition, desire, thirst to exist, to continue, to become more and more, is a tremendous force that moves whole lives, whole existences, that even moves the whole world. This is the greatest force, the greatest energy in the world. According to Buddhism, this force does not stop with the non-functioning of the body, which is death; but it continues manifesting itself in another form, producing re-existence which is called rebirth.

When this physical body is no more capable of functioning, energies do not die with it, but continue to take some other shape or form, which we call another life.

As there is no permanent, unchanging substance, nothing passes from one moment to the next. So quite obviously, nothing permanent or unchanging can pass or transmigrate from one life to the next. It is a series that continues unbroken, but changes every moment. The series is, really speaking, nothing but movement. It is like a flame that burns through the night: it is not the same flame nor is it another. Similarly, a person who dies here and is reborn elsewhere is neither the same person, nor another.

As long as there is this thirst to be and to become, the cycle of continuity (samsara) goes on. It can stop only when its driving force, this thirst, is cut off through wisdom which sees reality, truth, nirvana."

What the Buddha taught - p.33