Duccius[?] - inscriptions, notably a tombstone of Lucius Duccius Rufinus at York[2] (http://museums.ncl.ac.uk/archive/arma/contents/iconog/tombston/cent1/uk/york/duccius.htm)
... is:
6H2O + 6CO2 + light → C6H12O6 (glucose) + 6O2
In simple English terms, this is carbon dioxide plus water plus light (energy) yields oxygen plus sugar. ...