The main assumption in the field of the origin of life is that the early
living cells derives from the inanimate matter via a spontaneous process
of molecular evolution, namely a gradual increase of molecular complexity
and specificity till the onset of the genetic machinery. One of the consequences
of this view is that the transition to life can be in principle reconstructed
in the laboratory. The lecture will review the conceptual framework
and the operational assumptions implicit in these views; and will outline
the questions which are still unsolved, both conceptually and operationally,
in the pathway of the transition to life. In particular the difficulties
inherent in the RNA-world-approach as well as those present in the compartimentalistic
view will be presented. Finally the "top-down" and the "bottom-up" approach
to the construction of the early cell will be briefly discussed.