At the end of the 19th century she was known as the Welsh Fasting Girl and regarded as a miracle: the little 12-year-old who had not eaten for over two years.
In an age where spirituality clashed with the new teachings of science, she was an undoubted phenomenon, but whether or not her "miracle" was of her own making or something that was forced on her by manipulative parents remains unclear.
However you view it, the story of Sarah Jacobs is one of fascinating and tragic proportions. In the end she was killed by her own fame, a fame that, to begin with at least, she seemed more than eager to grasp.
Sarah Jacobs was born on 12 May 1857 on a farm just outside the village of Llanfihangel-ar-Arth in Carmarthenshire. Her parents, Evan and Hannah Jacobs, held respectable positions in this rural community, Evan having been a deacon in the local chapel. At the age of nine Sarah fell ill with convulsions of some type.
As she recovered she was allowed to sleep in her parents bedroom, a warm and comfortable environment compared to the loft where she would otherwise have spent her days. There was no denying that lying in bed all day, composing poems and reading the Bible, was far preferable to looking after the animals on the farm.
Spoiled and cosseted, she began to refuse food. She was genuinely religious but whether her refusal to eat had spiritual undertones or was simply the machinations of a manipulative anorexic has never been clear.
She was a self-possessed and bright child and, whatever the cause, she soon began to see the value in what she was doing. Perhaps her parents encouraged her in what was clearly a deception that fooled virtually everybody. Evan and Hannah later claimed that their daughter had had no food whatsoever from 10 October 1867 until her death two years later in December 1869.
As the fasting went on Sarah became something of a local celebrity, with people from the village wondering at her refusal to either eat or drink. And so it might have remained if the local vicar had not written to the newspapers about this amazing miracle that was occurring in his parish.
Sarah's fame was assured almost overnight. Soon people were coming from far afield, from the English cities as well as Wales, catching the train to Pencader and walking over two miles to the farm to stand gazing in wonder at this young girl who was defying the laws of nature. They brought gifts and money for her, dropping their sovereigns onto the bedspread as she lay, surrounded by flowers, reading and quoting the Bible.
Everyone marvelled at her appearance, one visitor remarking: "Her eyes shone like pearls, as alert as my own - - - She had rosy cheeks and looked like a lilly amongst thorns."
To live for over two years without food or water is, clearly, impossible but in the Victorian Age people really believed they were witnessing a miracle. How Sarah got her food is not known.
Some believe her sister was feeding her, passing titbit's from her mouth whenever they kissed. Others are inclined to the view that Sarah fed herself, climbing out of bed when the rest of the house was asleep.
Her body would have become used to reduced amounts of food, and she had often refused to eat her lunch in the past. When at school she had asked her classmates not to tell anyone, her parents in particular.
With her case attracting more and more interest, the vicar and the medical profession decided to mount a watch over Sarah. This was to last for a fortnight. Evan Jacob agreed but the watch did not last both day and night and the findings were unclear.
As Sarah grew fatter and plumper, reaching full maturity despite her lack of food, people began to suspect fraud. Dr Phillips of Guy's Hospital decided to organise another vigil. Six nurses were brought in to mount a 24 hour watch on the girl.
And now Sarah's position became really untenable. If she had previously been able to slip out of bed to find food in the night, now it was impossible.
She could not admit to fraud or lying; pride or religious conviction, or even her undiagnosed medical condition, would not let her. And so she simply lay there, waiting to die, as the nurses watched and made notes in their diaries.
The experiment was cruel: the nurses were instructed not to treat or help, simply to mount a watch. If Sarah asked for food they were to give it but otherwise they were to do nothing. And, of course, she did not, and the tragedy was to be played out until the bitter end.
The Lancet, the main journal of the medical profession, later commented that practitioners everywhere should be "filled with feelings of shame and indignation."
After four or five days Sarah lapsed into semi-consciousness and on 12 December 1869 she died. The 'miracle' was over.
An autopsy was held at the Eagle Inn in the village and a sticky substance and the bones of a small bird or fish were found in Sarah's stomach. Clearly, she had eaten something.
More tragic, however, were the grooves found on her toes - as if she had been trying to open the cap of the stone water bottle that had been placed in her bed, a desperate attempt to get water.
Evan and Hannah Jacob were subsequently convicted of manslaughter and spent 12 and six months, respectively, in Swansea prison. No-one could prove that they had deliberately starved and, eventually, killed their daughter but they - like the medical profession, although the doctors and nurses were never prosecuted - were certainly guilty of doing nothing to protect her. Perhaps they really believed they were witnessing a miracle?
So, Sarah Jacobs? A genuine miracle or a cynical exercise in fraud?
Many people call her Wales' first anorexic - and there are certainly elements of that awful condition in her history. But above all, this is the tragic story of a young girl on the threshold of life, a young life that was, because of her own personality or because of pressure from outside, cut brutally short.