Mary was born into a family that had close ties to Queen Elizabeth. Her father, Sir Henry Sidney, had been a close friend of Edward VI, and her mother, Lady Mary Dudley, was one of Elizabeth’s favourite attendants during the early years of her reign. Mary’s uncle, Lord Robert Dudley, was widely rumoured to be Elizabeth’s lover, prevented from marrying her only by the fact that he already had a wife.
Sir Henry was appointed Lord President of the Council of Wales before Mary’s birth, and the family spent much of its time in the Marches of Wales, where Mary was born. At a later period, Sir Henry was also Lord Deputy of Ireland, necessitating regular trips to Dublin, living in the castle.
There is no information about Mary’s education, but we can infer that she studied Latin as well as French and Italian. A knowledge of a Greek and Hebrew has also been postulated but cannot be proven. The Dudley and Sidney families had been part of the coterie of evangelical Protestants who surrounded Edward VI that valued female education, and took the education of Lady Jane Grey and the Lady (later Queen) Elizabeth, as models for their daughters. Mary was probably educated in the same way.
When Mary was fourteen, her sister, Ambrosia, died, and the Queen offered Mary a place at court, as a gesture of affection and sympathy to her parents. Her mother had attended court much less frequently after 1563, as she had been badly scarred by smallpox, after nursing the queen successfully through the disease. Elizabeth’s gratitude was not conspicuous, but now Lady Mary and Mary joined the court and were probably present at the great entertainment Mary’s uncle Robert, now Earl of Leicester, laid on at Kenilworth in 1575.
After two years as a maid-of-honour to the queen, Mary made a most advantageous marriage. Despite being only the daughter of a knight, the family’s proximity to Leicester made them sought after, and a marriage was arranged for her with the Earl of Pembroke. He was more than 20 years older than Mary, and already widowed, but such an age gap, although not the norm, was not uncommon.
There is no record of Mary’s feelings on the matter, and the only hint of their personal relationship comes in a letter many years later when Mary wrote that Pembroke was inclined to be of volatile temper. The couple certainly shared literary tastes, and the slight evidence of Pembroke’s will, suggests that he had faith and confidence in his wife.
Mary’s duty was to bear children and run the vast households that an earl required. She carried out both functions successfully, bearing two sons and two daughters, although one daughter died at the age of three, and the other in her early twenties.
As mistress of the great prodigy house of Wilton in Wiltshire, Mary presided over a ménage that encouraged poets, playwrights and actors. Pembroke was interested in drama as well, and Lord Pembroke’s Players were one of the leading groups of actors of the 1590s.
During the first half to the 1580s, Mary spent considerable time with her older brother, Sir Philip Sidney. Philip, although only 25 in 1580, was already forging a reputation as a diplomat, a poet, a committed supporter of the Protestant cause in the Netherlands, and a favourite of the queen. This steady progression in his career was interrupted in 1580 when he annoyed Elizabeth by writing against her proposed marriage to the French prince, François, Duke of Anjou.
He spent much of that year in exile from the court at Wilton, and it may be that it was at this time he introduced his literary friends, Gabriel Harvey, Edmund Spenser, Michael Drayton and others, to Mary. It was also during this time that he began his pastoral poem, The Countess of Pembroke’s Arcadia, dedicated to Mary.
Philip began a verse translation of the Psalms. It is not clear whether this was always intended as a joint project between the two, or whether Mary at this stage was just a sounding-board for his ideas.
Before long, Philip was back in favour with the queen and appointed as Governor of the Netherlands town of Flushing, after Elizabeth reluctantly agreed to give practical support to the Protestants of the Netherlands, who sought independence from their overlord, Philip of Spain. All of Mary’s family were supporters of the Protestant cause, and it is likely that she herself felt the same.
The war in the Netherlands was bloody, long-drawn out and inconclusive. In 1587, whilst Mary herself was seriously ill, Philip was wounded at the Battle of Zutphen, dying a few weeks later of gangrene.
Mary had already suffered the loss of both her parents that year, and the death of her beloved brother must have been one of the heaviest blows of her life. It can be inferred from some of her later work that she blamed the queen, in part, for the insufficiency of English military capability in the Netherlands which led to the disastrous battle.
Keeping the memory of Philip’s literary genius alive became one of Mary's core activities over the next decade, first in the promotion of memorial poems, and then in the development and preservation of his works. In 1593, she arranged the publication of the New Arcadia, as it has become known, a version of the poem extensively expanded and amended Old Arcadia, published by Philip’s old school-mate, Fulke Grenville, in 1590. The alterations and extensions in the New Arcadia probably derive from Philip’s own notes, but Mary may have added and enhanced some parts.
Mary’s own works began with two translations, one a philosophical work, the translation of du Mornay’s Discours de la vie et de la Mort, the other, the French play Marc Antoine by Robert Garnier. Mary’s version, Antonius was the first secular play by a woman to be published in England. The political undertones of the work, originally written in the 1570s, reflect the French Religious Wars, and the hopes for triumph of Protestantism. Following Mary's publication, the use of Roman or Greek history to point a contemporary moral or political point became widespread, in an era of censorship.
Mary also translated one of Plutarch’s Triumphs, that of ‘Death’, retaining the original 'terza rima', suggesting a high level of competence in Italian as well as skill in English.
The work for which Mary is most famous is her completion of the translation and versification of the Psalms, begun by her brother, Philip, who had only reached Psalm 43 by the time of his death. Mary completed the remaining 106, employing at least 128 poetic styles, emphasising the lyrical nature of the Psalms. The use of the Psalms for both public and private worship was an integral part of the Reformed faith, and Mary's most important source was the Geneva Bible, preferred by English Protestants to the official Bishop’s Bible, together with Calvin’s commentary.
The translation was dedicated to the queen, but was not published during Mary's lifetime, circulating in manuscript amongst the circle of writers who surrounded her. John Donne wrote an ode in praise of the work, likening Mary and Philip to Mariam and Moses.
Whilst Mary’s gift to posterity was her literature, and her patronage of writers, this was only a part of her life. As a countess, she had property to manage and a family to advance through maintaining relationship with her court network. She was on good terms with Lord Burghley until his death in 1598, and, to a lesser degree, with his son, Sir Robert Cecil.
She and Pembroke negotiated marriages for their children, although initial plans did not always come to fruition. Her daughter, Anne, was put forward as a bride for the Earl of Hertford, but the marriage did not take place before Anne's death. Mary’s oldest son, William, married one of the daughters of the Earl of Shrewsbury, who was a great heiress, despite having disgraced himself and been imprisoned for impregnating one of the queen’s maids-of-honour, then refusing to marry her. Mary’s second son, Philip, initially promised to Lady Bridget de Vere, made a private arrangement with Bridget’s younger sister, Susan, daughter of the Earl of Oxford, and grand-daughter of Lord Burghley.
Mary’s husband followed in her father's footsteps as Lord President of the Council for Wales and the Marches. Like Sir Henry, he found the role an expensive burden, with the queen unwilling to recompense him for all his costs. Fortunately, the Pembrokes had rather more resources than Sir Henry Sidney, and weathered the storm.
Mary was widowed in early 1600. William was not quite of age, which involved the Pembroke estates in all the expenses of wardship. Mary herself had several properties in dower, including Cardiff Castle plus two in Wiltshire. Cardiff caused her some problems and there are records of a legal case involving a dishonest or possibly violent, steward.
After the accession of James VI, Mary and her children were once again involved in court life, and entertained James and Queen Anne at least twice at Wilton. It is possible that the first production of As You Like It with Shakespeare and his colleagues in the Lord Chamberlain’s company was a performance at Wilton in front of the king.
In 1612, Mary travelled to Spa for her health, remaining abroad for some three years. During this period she became friendly with Matthew Lister, later a famous physician. Rumours spread that they were more than friends, and might have married in secret, but there is no evidence of a wedding.
Around the time of her return to England in 1615, King James granted Mary an estate near Ampthill, where she built Houghton House. The king may have visited her there in 1621, shortly before her death. Mary died at her London house on Aldersgate Street. There was a grand funeral at St Paul’s Cathedral, before her body was interred in Salisbury Cathedral, not far from Wilton.
Mary has long been considered the most influential, non-royal, female figure in literature and patronage of the late sixteenth century.