Blake claimed to experience visions throughout his life. They were often associated with beautiful religious themes and imagery, and may have inspired him further with spiritual works and pursuits. Certainly, religious concepts and imagery figure centrally in Blake's works. God and Christianity constituted the intellectual centre of his writings, from which he drew inspiration. Blake believed he was personally instructed and encouraged by Archangels to create his artistic works, which he claimed were actively read and enjoyed by the same Archangels. In a letter of condolence to William Hayley, dated 6 May 1800, four days after the death of Hayley's son, Blake wrote: