For one of those gnostics, the visible universe was an illusion or, more precisely, a sophism. Mirrors and fatherhood are abominable because they multiply it and extend it.
Para uno de esos gnosticos, el visible universo era una ilusion o (mas precisamente) un sofisma. Los espejos y la paternidad son abominables porque lo multiplican y lo divulgan.
Original text (Spanish)