It was William Blake who wrote of infinity in a grain of sand; there’s a logical, but also a peculiar parallel which happens unintentionally in Crucible, the first major retrospective exhibition of work by the late Neels Coetzee. It’s an odd thing, because the intensity and unequivocal beauty of the work you initially see is so great that you very quickly think you understand, and forgive its paltry quantity.

This damaging misperception has to do with an odd lack of information in the gallery that at first leads you to believe that Coetzee’s first major retrospective is really small and only fills Circa’s downstairs Speke Gallery. It doesn’t. The whole of the above gallery is full of his beautiful work, offering an aesthetic crescendo in your gallery experience which is without compare. Ignore the lack of signage and follow the ramp upwards after you have basked in the glory of the drawn images downstairs.

This aesthetic climax is Coetzee’s eponymous work, a peace monument comprising melted down AK-47 rifles. Completed in the mid-1990s, it’s a work which teeters between inaccessibility and the engaging rigidity of pattern. At the time, it was considered a landmark in South African sculpture, and has been placed in the gallery for this exhibition in such a way that it casts linear and complicated shafts of shadow and light around it.

The experience of seeing Crucible in this context bears great similarities with that of gazing upon an organ in a Gothic cathedral. It judders your emotions and it takes you a little while to gather yourself around the rest of the exhibition. Primarily showing sculpted works in the upstairs space of Circa, and many drawings, maquettes and etchings in the Speke space downstairs, the exhibition is heavily populated, yet feels bare: Coetzee, who passed away in 2013, was a highly self-critical artist, who often destroyed works in process.

So, in perusing this sensitively curated testimony to the value of Coetzee’s work, you understand – in the same way as you understand when you peruse Franz Kafka’s oeuvre, for instance – that this is the tip of the proverbial iceberg, but that the bulk of the body of a career trajectory of 39 years is sadly lost. There’s a deep and relentless focus on mortality with Coetzee’s bronze skull series. And there’s a monumentality to the individual works, which belies their maquette-like size.

In the gallery handout, there’s mention of the works being cast at two- or three times their original size, in compliance with Coetzee’s desire – something which was never honoured during his life time. In truth, the works could well have been cast ten- or twenty times their size, offering as they do a segueing of surfaces and a sense of space that is almost religious in its sense of mystery.

On the whole, a dark exhibition, in intent and focus, this retrospective conjures up a sense of deep sadness. The many monuments to the tormented, like broken gates, populate the gallery’s open vestibule, and one stands amid the fishes on the pedestal facing Jan Smuts Avenue.

Arguably, one of the exhibition’s most moving drawcards is the collation of two-dimensional works in the Speke Gallery. Coetzee’s approach boasted a very distinct line; one so delicate yet scalpel-like in its directness and intensity. He engaged with the stuff and texture of life with a curious and irascible exploratory eye and hand, creating a sense of intimacy which makes you draw close to, and away from, simultaneously.

A tremendously moving testimony to arguably one of South Africa’s more important sculptors, Crucible is not an easy exhibition to visit, but it is a deeply rewarding experience.

• Crucible, a retrospective exhibition of work by Neels Coetzee (1940-2013) is curated by Koulla Xinisteris. It is displayed at the Circa and Speke Galleries in Rosebank, Johannesburg, until September 26. On October 1, this exhibition will be segued with a response by artist Bronwyn Lace – one of Coetzee’s former students – to Coetzee’s life, work and death. Phone 011-788-4806 or visit circaonjellicoe.co.za