One of Śankara's most fundamental claims is that nirguna brahman,
‘unqualified reality’, is the origin of the world of experience. A serious challenge is
posed by the Sānkhyan philosophers in terms of a principle of material causation,
that the properties manifested in the effect are inherited from the material cause.
Since nirguna brahman and the experienced world are so different, the principle
implies that the former cannot be the material cause of the latter. Versions of the
principle in relation to alternative kinds of candidates for the role of material cause
are discussed, considering the particular cases which motivate both Śankara's and
the Sānkhyans' metaphysics alike. Śankara seems forced to accept an implausible
version of the principle by his own analysis of material causation.