What does an empty seat represent in early Buddhist iconography?

Question

Accepted Answer

In early Buddhist aniconic art (Sanchi, Bharhut, Amaravati), the empty seat (Vajrasana) under a parasol or Bodhi tree represents the Buddha's meditation and attainment of enlightenment at Bodh Gaya. The Wheel (Dharmachakra) = First Sermon; Stupa = Mahaparinibbana; Riderless Horse (Kanthaka) = Mahabhinishkramana (Great Departure).