One should always aim for sanity.
A healthy mind - emotional balance, clarity of thought, to be grounded in the present - and in plain and simple things.
To gain knowledge through psychosis implies that the knowing isn't earned - it is the reason certain truths are forbidden without initiation.
Unearned, immature knowledge can destroy a man's mind, send it reeling into rejection of reality and self - into a state of further fragmentation.
The price of dark thoughts is man's grip on reality itself.
It's not your soul the devil wants - but your sanity.