All wise men are dead…...

Can mean several things-

That the wisest men have all died, or

That wisdom itself is dead, or

That to be wise you have to be dead, or

That the wise thing to be, is dead, or

That no one alive is wise, or

That wisdom is the preserve of the dead, or

That we wise up as we get older

And then die before our wisdom is appreciated.

Or that wisdom is the cause of death

Or even that, death makes us wise!