Complex sentence: There is no family crest indicating the donor, who, given the expense of the book and its dating, must have been a high-ranking member of court; art historians speculate it was commissioned by or for Charles the Bold.
Split into simpler sentences: There is no family crest indicating the donor, who, given the expense of the book and its dating, must have been a high-ranking member of court. Some art historians speculate that it was commissioned by or for Charles the Bold.