Seeing Tzadikim and Gedolim

 Rav Eibschitz (Yaaras HaDevash 01:12) Meeting Sages – There are two benefits. The first is receiving beracha. Shefa and Tov  merely by seeing him. While seeing an evil person causes spiritual damage, seeing a saintly man is beneficial since the light of the Shechina is on him. This is indicated by the gemora (Eiruvin 13b) which notes that those scholars who benefitted from seeing Rabbi Meir’s back would have benefitted even more if they saw his front . 

Rav Eibschitz (Yaaras HaDevash 01:12) And there is another benefit to meeting the tzaddik and Sage , as they say, the sight of a tzaddik is a blessing, because while from some people who have an Evil Eye like Bilaam rays of light that come out of their eyes are harmful, so the rays of light that come out of a tzaddik is a blessing and their seeing us is good. Therefore there are two benefits from the tzadik -  one comes from seeing him and the other comes that he sees us. 

Eiruvin (13b) Rabbi Yehuda HaNasi  declared: The only reason why I am keener than my colleagues is that I saw the back of R. Meir, but had I had a front view of him I would have been keener still, for it is written in Scripture: But thine eyes shall see thy teacher