General Book of the Tarot, by A. E. Thierens, , at sacred-texts.com
The first sign or house in the Zodiac is the first step in the direction of Manifestation, and Aries is the High Priest as well as Avidya or Ignorance, standing before, c.q. above cognition. Potency and power are its attributes, because all and everything is immanent in this stage of Beginning. Power abstract, undeveloped, simple, but for that reason mightier than every detail or phenomenon, and the master of Nature. The ultra-positive, the very superior, and in the lower human sense the ultra-egotistical. Like the first note of a composition in music, it determines the tone and gives the key. From the First spring the Four, and so the symbols of the Four Elements appear on the table of the Magician, though his action, as far as action goes in this card and principle, exists in potency only and is indicated consequently in the wand in his right hand. In his superior abstractness he is eternal in relation to the phenomenal world, which is indicated by the symbols of Eternity above his head, the lemnescate, and around his waist, the serpent.
W.: "This card signifies the divine motive in man, reflecting God, the will in the liberation of its union with that which is above."
M.: "He symbolises Will."--This is exactly Aries.
P.: "The Unity principle, the origin of which is impenetrable to human conceptions, is placed at the beginning of all things." His upright attitude indicates "the will that is going to proceed into action."
The First house or Ascendant gives the key-note of the physical self, reflection of the Higher Self, and thus in the practice of divination the Magician
denotes the consultant, personally. In every figuration of cards it is further the 'beginning' and initiative.
As far as we may ascribe siderial meanings to the cards of the Greater Arcana, the Magician should rule the month of Aries, i.e. from the 21 March to 20 April. It appears gravely doubtful, however, if this may be considered to determinate incidental occurrences in time. It will certainly relate to properties of the sign Aries in general and in particular and consequently owned by people born between those dates. But for the rest definition of time, date or hour must be sought in the cards of the Lesser Arcana, as far as we know.