When you consider that epistemology of sankhya is strictly based on experience and induction the whole picture makes perfect sense. Absolute arranges itself into evermore subtle forms until mind emerges. Mind then looks back and solidifies that plethora of discreet and varied arrangements into perceptions / experiences out of otherwise uniform "substance" (for a crude analogy imagine a pointillistic painting).

The main argument in support of this view is death. That is, temporary nature of all forms. It is the only true absolute in the realm of phenomena and we cannot unthink it. Even in the most fantastic myths, there is no account of a person not dying. Rama, Krishna, Buddha, Jesus, etc. all died (even Elijah after he was taken by the whirlwind is later revealed to be alive and not in Heaven when Jehoram receives a letter from him). So, that's that.

Well, you can argue that mind solidifies death because it is bound to, but that essentially amounts to the same. And one would still have to explain how was mind shaped to behave in such a way when it is otherwise almost the most malleable form we know of.