To obtain an insightful understanding of protégés, mentors need to have a personal relationship with them. [...] This means that excellent mentors are accessible and available.  But they also need to exhibit the human skills of listening, caring, communicating openly, and giving constructive feedback.  To conclude, taking the time to truly know protégés is arguably the most important of the mentoring virtues.

- Elements of Mentoring by W. Brad Johnson & Charles R. Ridley.