A busy day for our Kiefer exhibition.   The private view last night was more crowded than I have ever known a private view, full of the European art crowd, young, rich and smart, all in their black suits.   Kiefer himself arrived, immaculately lean, mainly for the dancing at the after party.   Reviews have been wonderful, five stars in the Times, five stars in the Guardian.   And the experience of the exhibition is overwhelming, full of a relatively small number of monumental works, tracing his career from its beginning and including works which are fresh from the studio.   I strongly recommend seeing the exhibition in daylight because both the octagon, which contains a vast installation called Ages of the World, and the penultimate room, which contains seven grand works of wheatfields (they refer to the so-called Morgenthau Plan whereby Germany was to become farmland), are bathed in natural daylight.