Earth is the heaviest element, followed by water. Air is lighter, and fire is the lightest of all. It was believed that if all of the elements could be combined harmoniously and equally, the result would be the Philosopher’s Stone.
Fire is associated with the qualities of energy, assertiveness, strength, courage, transformation, and passion.  In Alchemy, it is considered the most important agent because it is used to fuel "the Work".
Water is associated with the qualities of emotion, healing, divination, and intuition. It is also associated with change. 
Air is associated with the qualities of intellect, study, youth, creativity, communication and travel. [ 
Earth is associated with the qualities of stability, order, grounding, fertility, material gain, and prosperity. 
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