the simile which has come in the tradition of jabir-ibn-abdullah ansari is as follows:
various benefits and effects are derived from the sun's existence even though it may be covered by a cloud. moreover, other benefits are derived from its rays if it is not covered by a cloud or rather anything else. imam too is the same.
i believe, this comparison has been made from two aspects and there exists two reasons for this (one aspect when the sun is covered by clouds and the other aspect when the sun is not covered by any object and its light glimmers) deriving benefit from the sun and making use of it by the living and rather the non-living creatures is something prevalent whether it is manifest or concealed under the clouds. every creature derives its own pleasure and share from it with the difference that when it is manifest and glimmering, the benefit derived is more than when it is covered and concealed. imam (a.s.) too is like the sun in these two afore-said cases.
this is the view of the shia-imamiyahs about imam (a.s.). however the sunnis believe that the benefits and effects derived from imam's existence is confined to the second type (i.e. non-absence of imam).
verily Mahdi is absent (amongst us) but attends the gatherings and meetings. he also speaks to the travellers and other people. rather, very often he presents himself during the haj season.
he wears the 'ehram' (pilgrim's garb), recites the call of 'labbaik', performs the 'tawaaf' (circumbulation) and concludes his haj by visiting his honoured grand-father and great fathers' shrines especially at times of special 'ziarats'. thus Mahdi is present amongst the islamic community but is not physically recognized.
one the contrary, we say: who can dare say that during the major occultation it is not possible to come in contact with Mahdi (a.s.) whereas historical and other books provide us with evidences that a section of people have received the honour of seeing and meeting him. this matter is not inconsistent with the tradition which says: 'if anyone claims that he has seen Mahdi, they reject his saying'.
this is because by context of the first part of the tradition it only means that anyone who claims the special deputyship should be denied.
rather we can say: Mahdi is one of the members of society and rather the most important member. it is possible that he acts upon his responsibility even though it may not be obligatory for him.
verily, it is possible that Mahdi may come in contact with the kings, rulers, princes and ministers and make some recommendations to them about reforms, maintenence of order and running of the affairs whether they follow his recommendation or not.