"In esoteric alchemy, the cross often represents the union of opposites and the process of transformation. It is a symbol that embodies the integration of various elements and energies to achieve wholeness and spiritual enlightenment.
The vertical line of the cross in alchemy is associated with the spiritual or celestial realm, representing divine energies or spiritual principles. It represents the transcendent aspects of existence, such as the connection to higher realms, spiritual aspirations, and the divine nature within.
The horizontal line of the cross is connected to the material or earthly realm, symbolizing the physical world, the human experience, and the manifestation of energies into tangible form. It represents the immanent aspects of existence, including the physical body, material reality, and the realm of matter.
The intersecting point of the cross represents the meeting or fusion of these opposing forces, symbolizing the alchemical marriage or the union of opposites. This union is seen as a necessary step in the process of spiritual transformation and the attainment of higher states of consciousness."
“By placing a rose, often representing love, beauty, and spiritual unfoldment, at the center of the cross, it signifies the harmonious integration and reconciliation of these opposing forces. It represents the unification of spiritual and material aspects, the blending of masculine and feminine energies, and the realization of a balanced and holistic spiritual path.”
In Ancient Egypt they had something similar to the cross called the ankh.
"In ancient Egypt, the ankh was a widely recognized and important symbol, often referred to as the “Key of Life” or the “Egyptian Cross.” The ankh resembles a cross with a loop or oval-shaped top, often interpreted as a stylized representation of a key. It was one of the most prevalent and enduring symbols in ancient Egyptian art and religious iconography.
The ankh was associated with life, vitality, and immortality in Egyptian culture. It symbolized the concept of eternal life and the divine power that sustained existence. It was often depicted being held by gods and goddesses, representing their ability to bestow life and divine blessings upon the living. "