Mulla Sadra, a Shi‘ite philosopher, uses both rational and theological arguments in defense of the infallibility of angels: "The sense of sin and fallibility is to contrast between lowly faculties and sublime faculties, where the soul wants superlative motives but motives and inner purposes contradict. These contradictions and contrasts are endemic to beings who are of a composite nature. In other words, beings are composed of contradictions and contrasting faculties, whereas angels are simple and not composed of anything." According to Sadra, the verse 16: 50 refers to infallibility of angels, in general.