saying: "Vesta is the same as the earth, both have the perennial fire: the Earth and the sacred Fire are both symbolic of home." The sacred flames of the hearth were believed to be indispensable for the preservation and continuity of the Roman State: Cicero states it explicitly. The purity of the flames symbolised the vital force that is the root of the life of the community. It was also because the virgins' ritual concern extended to the agricultural cycle and ensured a good harvest that Vesta enjoyed the title of Mater ("Mother"). The fecundating power of sacred fire is testified in Plutarch's version of the birth of Romulus and Remus, the birth of king Servius Tullius (in which his mother Ocresia becomes pregnant after sitting upon a phallus that appeared among the ashes of the ara of god Vulcanus, by order of Tanaquil wife of king Tarquinius Priscus) and the birth of Caeculus, the founder of Praeneste, who had the power to kindle or extinguish fires at will. All these mythical or semilegendary characters show a mystical mastery of fire. Servius's hair was kindled by his father without hurting him, and even his statue in the temple of Fortuna Primigenia was unharmed by fire after his assassination. Marriage Vesta was connected to liminality, and the limen ("threshold") was sacred to her: brides were careful not to step on it, else they commit sacrilege by kicking a sacred object. Servius explains that it would be poor judgement for a virgin bride to kick an object sacred to Vesta – a goddess that holds chastity sacred. On the other hand, it might merely have been because Romans considered it bad luck to trample any object sacred to the gods. In Plautus' Casina, the bride Casina is cautioned to lift her feet carefully over the threshold following her wedding so she would have the upper hand in her marriage. Likewise, Catullus cautions a bride to keep her feet over the threshold "with a good omen". In Roman belief, Vesta was present in all weddings, and so was Janus: Vesta was the threshold and Janus the doorway. Similarly, Vesta and Janus were invoked in every sacrifice. It has been noted that because they were invoked so often, the evocation of the two came to simply mean, "to pray". In addition, Vesta was present with Janus in all sacrifices as well.Servius (Ad. Aen. 1.292)