In early Buddhist art (before the emergence of iconic Buddha images in schools like Gandhara and Mathura), the presence of the Buddha was represented through symbols. These symbols were visual metaphors for key events in his life or his teachings. Common symbols included: the Empty Seat (representing his meditation and enlightenment or his absence after Parinirvana), the Wheel of Dharma (Dharmachakra, symbolizing his first sermon), the Bodhi Tree (representing his enlightenment), footprints of the Buddha, and the Stupa (symbolizing his Mahaparinirvana or final liberation).