The "uncreated light" is a term that can be found in mystical and theological writings of some Eastern Orthodox Christian theologians and mystics, particularly in the tradition of hesychasm. According to this tradition, the uncreated light of God is a divine energy or radiance that allows for a direct experience of God beyond concepts and language. This light is seen as being manifested in various places throughout the Old and New Testament, such as the burning bush (Exodus 3:2-6) and the transfiguration of Jesus (Matthew 17:1-9), among others.
In the context of hesychasm, the practice of prayer and meditation is seen as a way to access and experience the light of God within oneself. Through a process of purification and concentration, the person may be able to behold this divine light in a mystical experience.
It is important to note that the uncreated light is not a physical or visible light that can be seen with one's eyes, but a spiritual reality that is perceived through the spiritual senses of the soul. Some argue that the uncreated light is not a "thing" but rather the source of all things, including created light. Others believe that the uncreated light is a manifestation of the Holy Spirit, who is understood to be the bond of love between the Father and the Son.
In summary, the uncreated light of God is a mystical concept that points towards a divine energy or radiance that allows for a direct experience of God beyond concepts and language. It is a notion that reflects the contemplative and mystical dimensions of Eastern Orthodox Christianity.