Complex sentence: The king's sudden onset of insanity was seen by some as a sign of divine anger and punishment and by others as the result of sorcery; modern historians such as Knecht speculate that Charles may have been experiencing the onset of paranoid schizophrenia.
Split into simpler sentences: The king's sudden onset of insanity was seen either as a sign of divine anger and punishment or to have been caused by sorcery. Some historians such as Knecht speculate that he may have been suffering the onset of paranoid schizophrenia.