Complex sentence: It explores some major themes of daily life--corporate and personal charity, diet, sickness and mortality, servants--in a mosaic formed of documentary flashes of momentary insight into a multitude of obscure lives that can never be pieced together into individual biographies.
Split into simpler sentences: It explores some major themes of daily life: corporate and personal charity, diet, sickness and mortality, and servants. The mosaic is formed of insight into a multitude of obscure lives that can never be documented as individual biographies.