Sri Ramakrishna: The sannyasi must observe very strict discipline. He must not look even at the picture of a woman. But this rule doesn't apply to householders. An aspirant should not associate with a woman, even though she is very much devoted to God. A sannyasi, even though he may have subdued his passions, should follow this discipline to set an example to householders.
Worldly people learn renunciation by seeing the complete renunciation of a monk; otherwise they sink more and more. A sannyasi is a world teacher.
Source: Gospel of Sri Ramakrishna