writers divided history periods six ages four empires considered time last end world ref name mommsen mommsen petrarch 's conception 'dark ages' ''speculum'' pp ref referring times spoke modern ref name dailyx singman ''daily life'' p x ref italian humanist poet petrarch referred pre christian times ''antiqua'' ancient christian period ''nova'' new ref name idea knox https webarchiveorg web http wwwboisestateedu courses latemiddleages renaissance historyrenshtml history idea renaissance ref petrarch regarded post roman centuries dark compared
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