To elaborate: consider the formal sentence «x is Ø,» where Ø stands for an ensemble
of sense data associated with the alleged substantial entity, x. Let x = «billiard ball,» and we can associate a definite Øb» a set
of properties in a
descriptive sentence corresponding to
sense data in an ensemble actually characterizing a portion
of our perceptual space, consisting
of things like sphericity, hardness, color, elasticity and the like.