Joseph Beuys might be one of the most influential artists of the 20th century, but he is a difficult artist to exhibit. So much of his work was in performance, existing now only in grainy photographs and a few props, like the relics of a saint.

This exhibition, part of the ARTIST ROOMS project, is a rare show of more than 100 drawings spanning 40 years, the most important collection of these outside Germany. Beuys drew prolifically, to work out his ideas, to plan performances and sculptures, and as works in their own right, particularly in his abstract Braunkreuz series.

He drew spontaneously, with whatever was to hand, on scraps of torn paper and hotel room notepads, as well as with certain symbolic materials such as hare's blood. Early drawings are often symbolist in approach, featuring animals or female figures, though he tried his hand at geometric abstracts too. Among the later works are plans for scientific experiments, notes for 'actions', a draft manifesto for a political party.

Each work is accompanied by extensive explanatory text and, to be fair, we need it. Immediate as these drawings were, and important as they are for historical record, they don't bring us easy insights into Beuys' mind. Mostly, they remind us how singular and multi-faceted that mind was, and how difficult it is to recapture its essence.

Scottish National Gallery of Modern Art, Edinburgh, until Sun 30 Oct, free.