To my shame, I entered the current major Royal Academy exhibition of the work of Anselm Kiefer ignorant and unprepared. The artist doesn't leave you wondering for long: it is shock and awe from the first moment in the first gallery. Kiefer's work is big in every sense - monumental scale, huge mythic themes, and an obsession with alchemy, with some 'canvasses' being huge sheets of lead studded with diamonds. Underlying all this is a technical brilliance: mastery of texture and perspective, which, in combination with the scale of the works, makes for an immersive experience. This immersion involves both the visual and the ideational - Paul Celan's poems form the theme for many of the paintings on show and their words snake across the canvass of some of them, supplying visual effects as well as ideational content.

Kiefer's would seem to be in essence identity art: he asks identity questions at the elemental level about our mineral (al)chemical nature and its transformational possibilities, and vegetable products feature in some of the works, again adding to the textural richness. At the social and cultural levels of identity the focus is Germanic: on Germanic myths, on their re-occurring elements such as the forest, on the political echoes and uses of German myth in Nazism, and on war.

The first works in the Royal Academy exhibition plunge you into Kiefer's brave exploration of the roots of Nazi identity: early works by which it seems he announced himself forty years ago. In a landscape of rich park- and lake-land with stone monuments, reminiscent of, say, Potsdam, a small black figure in a world war two greatcoat, gives the Nazi salute, a gesture forbidden under current German law. The figure, we understand to be Kiefer himself, in this case wearing his father's greatcoat from his war service. (Kiefer's own figure frequently appears in the paintings, often prone, as though absorbing or perhaps acting as a reference-point for those paintings other messages.) His quality of immersion is at its most effective in huge canvasses of neo-classical Mittel Europa interiors, where the grand and terrible modern myths were played out, interiors portrayed as in a state of almost organic dissolution, and in depictions of the frozen landscapes of war.

These canvasses have an enormous emotional impact on the viewer, even though they have an ambiguity: the questions of the influence of symbol and myth on German history are raised but not resolved in the works, and one can only speculate on Kiefer's own views. Perhaps there is a hint of a post-modernist relativism in one of the last works on display: a huge diamond-studded sheet of lead. The surface of the lead had a richly varied patina, and, as my daughter pointed out, the varying pattern of lights sparkling from the diamonds altered your perception of the space and surface texture as you moved in relation to it. This is Kiefer's immersion trick, combining control of texture and perspective, deployed in a more abstract, less immediately disturbing, but perhaps ultimately more thought provoking way.