Complex sentence: Regarding miraculous cures, Kardec wisely states that these, if frequent enough, would have been a hindrance to the development of mankind: if people could be miraculously cured man would not pursue knowledge.
Split into simpler sentences: Regarding miraculous cures, Kardec wisely states that these, if frequent enough, would have been a hindrance to the development of mankind. If people could be miraculously cured man would not pursue knowledge.