Some chemical solutions rotate the direction of vibration of polarised light despite the fact that their constituent molecules are randomly orientated and are continually jostled by thermal agitation. There is no trace of a regular lattice in this case and there is no need for a permeating field. All that is necessary is that the molecules of the dissolved substance (the solute) can exist in both ‘left-handed’ and ‘right-handed’ forms and that one of them predominates in the given solution. Just as gloves, and hands, come in mirror image pairs (a left and a right), some molecules come in left-and right-handed forms and their property of handness is called chirality. The word chiral comes from the Greek cheir ≡ hand.