The Twenty-ninth Spirit is
Astaroth. He is a Mighty, Strong Duke, and
appeareth in the Form of an hurtful Angel riding
on an Infernal Beast like a Dragon, and carrying in
his right hand a Viper. Thou must in no wise let
him approach too near unto thee, lest he do thee
damage by his Noisome Breath. Wherefore the
Magician must hold the Magical Ring near his
face, and that will defend him. He giveth true
answers of things Past, Present, and to Come, and
can discover all Secrets. He will declare wittingly
how the Spirits fell, if desired, and the reason of
his own fall. He can make men wonderfully
knowing in all Liberal Sciences.

The advice you get is not always the advice you need.

Also: sometimes you need the obvious thrown in your face to realize it.

Where is that quotation from?