may be called “intuitive” knowledge, and the truths so known may be called “self-evident” truths. Among such truths are included those which merely state what is given in sense, and also certain abstract logical and arithmetical principles, and (though with less certainty) some ethical propositions. Our “derivative” knowledge of truths consists of everything that we can deduce from self-evident truths by the use of self-evident principles of deduction.