There are some things perfectly known, as the Circle of Ascension; some in a competent measure, as the Revolution of the Sun; some may be known although they yet are not, as the Revolution of the Superiors; some things fall under knowledge, yet cannot be exactly known, as the precise Ingress of the Sun into the Equinoctial point; some are neither known, nor can be known, as the complete commixtures and distinct virtues of the Stars. - Cardan Girolamo (1501-1576)