'People buy it to ward off lightning. They smear it on their bodies so they can go outside when the sky is thundering.'
Further along the shelf was a row of jam jars with soft white chunks like marshmallows floating in a brown liquid. 'Python flesh: that's for strength when a man enters a woman.'
The cure for a headache was the bark of the black stinkwood tree. 'You crush the bark, you put a bit of the powder under your nose, you inhale, you sneeze and then the headache's gone.'
The shop was small, dark and musty. Lining the shelves were 30 species of bark in boxes, pumice stones, incense sticks and desiccated plants. Hanging from the ceiling were snakeskins and animal pelts. 'This is monkey fur,' said the shopkeeper, an elderly Indian man with grey plaited hair. 'When children have bad dreams you burn the fur at night inside your house and it keeps the bad dreams away.'
Muti - pronounced 'mootee' - is the Zulu word for medicine. It is big business in South Africa: more than 70 per cent of the black population resort to traditional African ways when beset by ill health and sales fetch close to one billion rand (pounds 200m) a year.
Professor Siegfried Drewes is the head of chemistry at the University of Natal, which has been researching muti for the last 25 years. 'We have yet to establish a sound scientific footing for the capacity of herbal medicine to provide a cure for any ailment,' he said. 'On the other hand, we haven't come up with a sound scientific basis for refuting the value of muti.'
The bark of the black stinkwood, the muti equivalent of aspirin, has been found to contain over 30 chemical compounds. The task of isolating them and then subjecting each to rigorous investigation takes many years. 'There are so many unexplored flora in Africa that it will take more than 100 years before we can say for certain whether certain types of muti work or not,' said Professor Drewes.
He himself acknowledged that he did not use muti, being uncertain as to the long-term effects or dangers of overdosing. 'But you can't deny the element of faith in achieving successful medical cures.'
Muti, as displayed by the properties attributed to sperm whale fat, is believed to do far more than address health problems, however. Thandeka Miya, an anthropology student at the University of Natal, said muti was considered by believers to provide the antidote to every conceivable problem.
Ms Miya has been researching muti that wards off bullets, a particularly marketable commodity in the province of KwaZulu-Natal, where even by South Africa's notorious standards, violence and crime yield a spectacular number of deaths each year.
'The potion that the inyangas use contains gun-powder, mercury, a piece of elephant skin and the hand and eye of a baboon. The point of the elephant skin is that it is very thick and cannot be penetrated by ordinary guns.
'A young man who said he had survived an attack by gunmen on his home told me that when you go to the inyanga (medicine man) he tells you to take off your clothes, he gets out a razor, dips it in the muti and then makes small cuts on your breast-bone, your back, your temples: that is so the bullets don't penetrate your most vulnerable areas.'
Ms Miya, who remains sceptical, had not been able to establish what the baboon parts were supposed to bring to the potion.
What she did know was that baboons were associated with the bad muti used by witches. 'Last month a small boy in Clermont told the police that his mother was bewitching people, that she sent baboons to people's houses at night.
When people found out about this they tried to kill the mother and the police had to rescue her.'
The belief, widespread in the Zulu community, is that witches ride baboons backwards to the homes of their enemies - or their clients' enemies - and smear potions of evil muti on the doors. The victims can then be afflicted with barrenness, dementia or terminal sickness.
For the most part, however, muti is understood to have beneficial effects.
The elderly Indian shopkeeper said he had a black, creamy potion which, when applied to the doors, prevented your car from being stolen. He also had a white grease that you rubbed into your eyebrows to guarantee success at job interviews.
When asked what was the most powerful magic in the shop, he replied, surprised and a little indignant: 'Magic? No. We have no magic here.'