  At other times, the cognitive reliability of the Forms seems grounded in the analyticity, or logical certainty, or necessity, that holds between the essence of a Form and various properties ‘discernible in its nature.’ Looked at in this light, the factor responsible for the deficiency of sensibles is that their properties are contingently related to them, in contrast to the Forms whose properties are necessarily stuck to them with ‘logical glue’ (see Vlastos 1969; Code 1993).