Concerning the evil planetary spirits, the spurious Fourth Book of Occult Philosophy, attributed to CORNELIUS AGRIPPA, informs us that the spirits of Saturn “appear for the most part with a tall, lean, and slender body, with an angry countenance, having four faces; one in the hinder part of the head, one on the former part of the head, and on each side nosed or beaked:  there likewise appeareth a face on each knee, of a black shining colour:  their motion is the moving of the wince, with a kinde of earthquake:  their signe is white earth, whiter than any Snow.”  The writer adds that their “particular forms are,—­
     A King having a beard, riding on a Dragon. 
     An Old man with a beard. 
     An Old woman leaning on a staffe. 
     A Hog. 
     A Dragon. 
     An Owl. 
     A black Garment. 
     A Hooke or Sickle. 
     A Juniper-tree.”

Concerning the spirits of Jupiter, he says that they “appear with a
body sanguine and cholerick, of a middle stature, with a horrible
fearful motion; but with a milde countenance, a gentle speech, and of
the colour of Iron.  The motion of them is flashings of Lightning and
Thunder; their signe is, there will appear men about the circle, who
shall seem to be devoured of Lions,” their particular forms being—­
     “A King with a Sword drawn, riding on a Stag. 
     A Man wearing a Mitre in long rayment. 
     A Maid with a Laurel-Crown adorned with Flowers. 
     A Bull. 
     A Stag. 
     A Peacock. 
     An azure Garment. 
     A Sword. 
     A Box-tree.”

As to the Martian spirits, we learn that “they appear in a tall body,
cholerick, a filthy countenance, of colour brown, swarthy or red,
having horns like Harts horns, and Griphins claws, bellowing like
wilde Bulls.  Their Motion is like fire burning; their signe Thunder
and Lightning about the Circle.  Their particular shapes are,—­
     A King armed riding upon a Wolf. 
     A Man armed. 
     A Woman holding a buckler on her thigh. 
     A Hee-goat. 
     A Horse. 
     A Stag. 
     A red Garment. 
     Wool. 
     A Cheeslip."[1]

[1] Op. cit., pp. 43-45.

The rest are described in equally fantastic terms.

I do not think I shall be accused of being unduly sceptical if I say that such beings as these could not have been evoked by any magical rites, because such beings do not and did not exist, save in the magician’s own imagination.  The proviso, however, is important, for, inasmuch as these fantastic beings did exist in the imagination of the credulous, therein they may, indeed, have been evoked.  The whole of magic ritual was well devised to produce hallucination.  A firm faith in the ritual employed, and a strong effort of will to bring about the desired result, were usually insisted upon as essential to the success of the operation.[2]