He used unusual, eccentric, and sometimes cruel techniques to try to increase her fortitude, such as firing blanks at her skirts, dripping hot wax on her arms, and having her wade into a lake fully dressed to test her resilience to cold water.

He then arranged for Sidney to undergo experimental vocational and residential changes—first attending a boarding school, then becoming an apprentice to a dressmaker family, and eventually being employed as Day's housekeeper.

Having seen changes in Sidney, Day proposed marriage, though he soon called this off when she did not follow his strict instructions; he again sent her away, this time to a boarding house, where she later found work as a lady's companion.

[1] This person left a note explaining that the baby's baptismal name was Manima Butler and that she had been baptised in St James's Church, Clerkenwell.

Described as having a face pockmarked from smallpox, a brooding personality, and a short temper, Day attended Corpus Christi College, Oxford, to study philosophy.

Inspired by the character of Sophie in Rousseau's Emile, he resolved to "create" his ideal wife by raising her from adolescence, using the techniques laid out in the book.

[9] Day was approaching financial independence, when he would have full access to the money left to him, and conspired with his barrister friend, John Bicknell, to find two girls who could be taken into his care to be groomed as a perfect wife.

[11] Just after Day's 21st birthday[12] in June 1769, he and John Bicknell travelled to the Shrewsbury Orphan Hospital to choose the first girl for his experiment.

Sidney was 12 years old at the time, described as "a clear auburn brunette, with darker eyes more glowing bloom and chestnut tresses".

Instead they told him that she was to be indentured as a servant at Edgeworth's country house in Berkshire, waiving the £4 (equivalent to £701 in 2023) fee they would have received for the apprenticeship.

[11] In line with the orphanage's requirements that responsibility be held by a married man, Edgeworth would be legally accountable for Sidney, despite him not being present nor even aware of the arrangement.

[17] Day became a benefactor, and subsequently governor, of the Foundling Hospital, and on 20 September 1769 he chose another girl for his experiment, renaming her Lucretia[18] after the Roman matron.

[13] Day wished for the girls to be isolated from external influences while he educated them so, at the beginning of November 1769, he decided to move them to France.

Finally, he wanted to be able to debate complex concepts with them, so he taught them rudimentary theories in physics and geography, tasking them with observing the changing of the seasons, and recording details of sunrises and sunsets.

[28] Accounts by 19th-century historians suggest that Day grew impatient with the girls when they became bored with their lessons and began to squabble, and that he also spent significant time nursing them through a bout of smallpox.

[29] Day apprenticed Lucretia to a milliner in Ludgate Hill, and took Sidney to Stowe House in Lichfield, where her training could continue.

[33] In an attempt to increase her resistance to pain he would drop hot sealing wax on her back and arms or stick pins in her, commanding her not to cry out.

[34] To increase her resistance to the cold, Day instructed Sidney to wade into Stowe Pool until the water reached her neck, then lie in the nearby meadow until her clothes and hair had dried in the sun.

Finally, to test her resistance to luxury, he gave her a big box of handmade silk clothes and had her throw them on a fire.

Sidney became able to endure hot wax dripped on her arm without flinching, but she did tell others of his secret techniques, and could not help screaming whenever he fired his gun at her.

[35] During their time at Stowe House, Day introduced Sidney to members of the local intellectual circle, including the priest at Lichfield Cathedral, Thomas Seward.

Day appeared to accept Edgeworth's point of view, as he paid for Sidney to attend Sutton Coldfield boarding school in Warwickshire early in 1771.

[45] Over the next few months, Day returned to moulding Sidney to meet his requirements for the ideal woman, choosing what she would wear, and pushing his ideas of frugality upon her.

When he returned to find her in an outfit that did not meet his requirements, he flew into a rage and Sidney fled for a few hours, so Day called off the engagement.

[49] "I never thought I had a right to sacrifice another being to my own good or pleasure; but whatever else ensued you would be placed in circumstances infinitely more favourable to happiness than before" After her engagement to Day ended, Sidney spent eight years at boarding houses around Birmingham.

She contacted Day for advice, and he told her in absolute terms not to marry Wardley, even writing an acrostic poem for her to use in turning him down.

[60] Sidney found a role as housekeeper for Charles Burney,[61] as well as general manager of his schools in Chiswick, Hammersmith, and Greenwich.

[62] Sidney asked her friends not to discuss her past as she believed her humble beginnings, and Day's mistreatment of her, would tarnish her reputation.

[68] Strong parallels have also been drawn between Sidney's upbringing and two novels of 1871: Henry James's Watch and Ward,[69] and Anthony Trollope's Orley Farm.

[70] The story of her life has been told in Wendy Moore's 2013 book How to Create the Perfect Wife[68] and dramatised in the 2015 BBC Radio 4 play The Imperfect Education of Sabrina Sidney.