"The leadworks are distinguished by the predominance of the lead ground and the absence of translucent glass. Were they not occasionally reminiscent of stained glass work, one would perhaps approach them as pictures or sculptures that were created from a completely different perspective. The two elements of lead, a material that has been associated with death since time immemorial, and glass, a material through which the light shines out, assume a particular meaning in connection with the theme of memento mori; this significance is further increased when viewed in the context of stained glass. From the earliest of times, the leads in a stained glass panel have had a dual function: as a supporting structure for the glass pieces and as a conspicuous, graphic network of dark lines. However, with a few exceptions, the lead network is generally subordinate to the composition of the light, forming the technical framework for it – its skeleton. Clarke however completely upturns the usual values and the importance of the materials and the relative lightness to darkness are reversed in these works of his. Grief caused light as well as colour to drain from the artist’s life, and transience emerges as a recurrent theme in his work. Even the inscriptions, which would traditionally stand out on pale glass and be clearly legible, are here rendered as faintly gleaming letters on a darkly shimmering lead ground." – Vitromusée Romont director Stefan Trümpler in the book Life and Death, catalogue of the 2010 exhibition at the Swiss National Museum of Stained Glass.