Inward light, Light of God, Light of Christ, Christ within, That of God, Spirit of God within us, Light within, and inner light are related phrases commonly used within the Religious Society of Friends (Quakers) as metaphors for Christ's light shining on or in them. It was propagated by the founder of the Quaker movement, George Fox, who "preached faith in and reliance on 'inward light' (the presence of Christ in the heart)". The first Quakers were known to sit in silence and meditate on the words of the Bible until they felt the inward light of God shining upon them and the Holy Spirit speaking. The concept was highly important to early Quakers, who taught: "God reveals Himself within each individual's conscience and consciousness by the Holy Spirit, Christ Himself being the Light to illuminate man's sinfulness and lead in the way of truth and righteousness. ... this light is in all men by the grace of God to lead them to Christ, and that the same light will give daily guidance to the Christian." The Key to the Faith and Practice of the Religious Society of Friends states that the Inward Light is "both the historical, living Jesus, and as the Grace of God extended to people that simultaneously makes us conscious of our sins, forgives them, and gives us the strength and the will to overcome them" and "teaches us the difference between right and wrong, truth and falseness, good and evil". As such, the word light is commonly used by Christians (including Quakers) as a metaphor for Christ, derived from many Biblical passages including John 8:12, which states: I am the light of the world. Whoever follows me will never walk in darkness, but will have the light of life. Quakers take this idea of walking in the Light of Christ to refer to God's presence within a person, and to a direct and personal experience of God, although this varies to some extent between Quakers in different yearly meetings. Quakers believe not only that individuals can be guided by this light, but that Friends might meet together and receive collective guidance from God by sharing the concerns and leadings that he gives to individuals.