Many of the presumptions above enumerated are based upon no inference of fact, and are what are known as "false presumptions of law." Among these may be mentioned the presumption of innocence, of a prior lost grant, that the subscribing witnesses to a thirty-year old document are dead, that children under seven years of age are incapable of committing crime, that every man knows the law, that an insane mind is incapable of entertaining a criminal intent, that written contracts cover and merge all previous verbal agreements and negotiations, of malice in uttering or publishing of words actionable per se, and that every person intends the natural and probable consequences of his acts.