Just as both sugar and flour being white look alike, but can only be identified when tasted (one is sweet, the other insipid).
Just as brass and gold bear the same colour, but when both are placed before an examiner, the value .of gold is known.
Just as both a crow and a cuckoo is black in colour, but they can be distinguished by their voice. (One is sweet to the ears while the other is noisy and irritating).
Similarly, outer signs of a real and a fake saint look alike but their actions and characteristics can reveal who is genuine among them. (Only then can one know who is good and who is bad). (596)