Stumbling around in the semi-darkness of a rather remote and labyrinthine corner of the Castle of Good Hope, armed only with the name of the artist, the title of the exhibition to be reviewed, and a rather ineffectual fold-out Month of Photography map, my ears prick up at the thin strains of a tune played on a radio - an unusual and unexpected sound in this architectural bastion of South African history. Scrambling after the tinny sound which, judging from Lien Botha's choice of title, should lead me to her exhibition, I begin a rather steep and somewhat treacherous climb (visitors, beware of overactive children taking delight in the dim recesses of this building) to what I hope is my destination.

Reminded of Dante's journey, I am led up to a room bursting with light, sound and, thankfully, fresh air: while the venue offers a relief from the somewhat dingy, low-ceilinged rooms making up this space, Botha's exhibition, in its presentation of delicate and at times poetic photographs, appeals to the viewer's visual sensibilities in a way that is itself a proverbial "breath of fresh air".

On entering the exhibition space, the viewer is greeted by two large hessian sacks, one spilling a mound of raw cotton, and a virulently red radio (my guide) tuned to a local station. At first glance, the significance of these objects eludes me, and I turn for further clues to the photographic part of the installation: two series of images, evenly interspersed between each other, surrounding the installation piece. The first series is an almost sensual depiction of the diffuse, late afternoon Florentine light as it plays across the rough surface of a fabric structure, while the second comprises crisp, high-resolution representations of the lifecycle of a species of moth indigenous to South Africa. Appearing at first to be wholly unrelated, the two sets of images, on closer inspection, begin to resonate with echoes that set the tone for the subtle (if perhaps tenuous) visual dialogue at the heart of Botha's exhibition.

Taken during a residency in Florence, the first set of images plots Botha's fascination with marketplace stalls along the Mercato di San Lorenzo. Intrigued by these temporarily erected structures and, more importantly, the manner in which the afternoon light filtering through the fabric walls implied "a world of transience, sacred rituals and seclusion", Botha presents the viewer with diffuse, slightly out of focus shots which intimate, through strong contrasts between light and shadow, the presence of ephemeral, elusively liminal spaces.

The visual and thematic resonance between the cocoon/chrysalis of the moth and its metamorphic lifecycle, and these transient, mutable spaces, while a little strained, is no doubt fairly obvious. In the same way, the delicate fragility of the moth, pinned to its polystyrene bed, serves to emphasise the impermanence of these structures and the spaces they enclose. In the museum-like displays of classified and categorised moths, juxtaposed with at times shroud-like folds of fabric, it can be supposed that Botha addresses the transience of mortality and the inevitability of death.

Resplendent with visual and metaphoric allusion as the images are, I am nevertheless forced to consult the artist's statement in order to try and "tie up" the various threads, and in the process weave together the separate components of this exhibition. After reading in the catalogue of Botha's encounters with three Marys (one of whom is mentioned for her connection to the silk trade and her gift to Botha of a small radio - "the size of a human heart"); of a family heirloom destroyed by clothes moths, and memories of a grandfather's cotton fields at sunset, it becomes more evident that Botha's exhibition reveals a concern with the impermanence associated with the continual process of becoming; the transitory nature of experience; and the ethereality of memory.

While Botha acknowledges that the links running throughout her exhibition are "subtle, perhaps even fractured", my impression is that these links, although discernable, are at times a little too fractured, with the result that the exhibition, beautiful in its delicate evocation of universal concerns, is marred by the fact that an acquaintance with the artist's personal experience becomes necessary in order to fully access and appreciate its poignant thematic exploration.