Back in the days, whenever a sculptor would make a mistake while carving the marble sculpture, they would use a wax to fill in their mistakes.

Thus, a sculpture without any wax would be considered truly great piece of work, a masterpiece - there is no flaw, it is authentic and pure in its form.

Translated, the latin word for ‘without‘ is sine and ‘wax’ is cera and with these words combined produces sinecera later developed into a word, sincerely.

… of course, this is all just a story.