In order for manifestation to occur, that is for things to happen, there has to be a spark of intuitive inspiration that incites action. That is the commonality between all three fire signs in the Zodiac; Aries, Leo, and Sagittarius. The fire signs move along the evolutionary trajectory with the expression of their intuition at the forefront, always expressed outwardly, pulling it into action, away from the recessive state of reflection and contemplation. This is the Yang energy in motion, existing for movement, for ignition. Fire is the element of exploration, of intuitive understanding via results.
As Fire moves alongside the Zodiac their understanding of their own intuitiveness and inspiration changes focus but never intensity. We can see it begin in Aries, as a creative force to try anything and everything, to assert their individuality with their strong sense of boundless energy, for their intuition comes from instinct. Travelling along the Zodiac we see the evolution of intuition in Leo, where the sense of self is undeniable, therefore their self expression now becomes paramount, and their intuition comes from inspiration. How can they be inspired and how can they inspire others? This becomes a call for validation of action, because action and the self become one when expressed in the shining energy of Leo.
The Zodiac wheel is round because the Soul is eternal, it will need to continuously go on different journeys, within different phases, always with the intent of moving alongside the evolving awareness of the Universe. This truth is felt the strongest by Sagittarius, whose intuition is orientated to the bigger picture exposed by this expansion. Their inspiration comes for the intuitive belief that there is something bigger and brighter around the corner, they have to explore it, know it, and integrate it to their truth, and that through living that truth through goals and knowledge outside of what they already known, is what inspires them to action.