‘Art’, Tilson has written, 'is a symbolic discourse of which mankind alone is capable… I think of art as a tool of understanding, an instrument of transformation to put yourself in harmony with the world and with life … The basic given data of experience and the physiological and psychological aspects of procreation, birth, growth and death remain relatively unchanged.' The themes Tilson chooses for his work aspire to transcend time and cut across cultures to communicate the sacred in nature via references to pre-classical mythology, the Norm American Indians, the Dream Time of the Australian Aboriginals, and alchemy. Modular structuring devices - the letters of the alphabet, the days of the week, the circular mnemonic devices of Alchera which relate to the four Cardinal points, to the four Elements and to the four Seasons, the lunar months, labyrinths, ladders, words, symbols - are assembled in matrices layered with complex universal meaning.