The minor arcana (”lesser secrets”) contain a beautiful gradation of power. Their spectrum aligns with the journey of the sun: one card for each decant of the Zodiac, 3 cards for each sign, 9 cards for each season, and so forth. This arrangement applies to most any Tarot deck, though Crowley has a somewhat more intricate format for the minor arcana based on Thelemic practices.
The minor arcana are more geared towards nuance and conditional aspects of life. From the four suits we gather the four tools of the magician: The Wands (Willpower), The Cups (Intuition), The Swords (Intellect), and The Pentacles (Body). It is through these devices which we perceive and take action in our world. The cycle of the numbers 1 through 10, corresponding with the 10 Sephirah on the Tree of Life, guide us through the degrading process of manifestation of the will.
The minor cards are vital in completing the picture when performing Tarot readings. They aid in providing details and aspects to the message. Knowing these cards well will improve the quality of Tarot readings as they blend with other minor cards and elaborate on major cards.