  On this Sautrāntika view, as presented by Vasubandhu, perceived  material properties, both primary (e.g., solidity) and secondary  (e.g., color) are in fact emergent properties of subtle collections  of elements whose phenomenal properties reflect the constitution and  function of the perceptual systems. For instance, fluidity in the  case of water may be classified both as a primary property of water  atoms and also as a secondary property reflecting a specific  configuration of water atoms. The same atoms of water, when  configured as ice, may produce the sensation of hardness instead of  that of fluidity.