For generations they have educated Scotland's elite - individuals who have gone on to achieve power, fame and fortune in the worlds of politics, business, the arts, television and sport.
Today, for the first time, the scale of the income generated by the nation's leading private schools can be revealed.
According to a list of the top 300 Scottish charities in terms of income, 17 of the nation's leading independent schools generate more than £160m between them in fees every year.
Yet that combined income does not come close to the money generated by the two charities which, when you take those which are jointly registered in England and Wales out of the equation, come top in the overall list from the Scottish Charity Register.
The first 20 charities have a total income in excess of £4bn, accounting for 38% of the sector's £10.9bn. Of the 20 charities with the greatest incomes, more than half are also bodies registered as charities in England and Wales; and seven are universities.
The solely Scottish charity with the largest income is Edinburgh University, with £439m a year, followed by the University of Glasgow with £312m.
A spokesperson for the University of Edinburgh said: "In common with all publicly funded UK universities, the University of Edinburgh benefits from charitable status. The University of Edinburgh is amongst the UK's 10 largest universities and is accountable to a number of bodies including the Scottish Funding Council and Office of Scottish Charity Regulator (OSCR)."
The Church of Scotland, with an annual income of £108m, is 20th on the list while the Marie Curie Cancer Care, RSPB and Quarriers are 28th, 33rd and 48th respectively. The list of educational charities is topped by the Edinburgh Merchant Company, 43rd in the overall list, which now runs three of Scotland's most successful independent schools.
Formed by Royal Charter in 1681 as an organisation to protect the trading rights of merchants in Edinburgh, as it grew in influence, charitable trusts were often left to the company to be administered.
In this way, it came to operate several hospital schools, including the Merchant Maiden Hospital, George Watson's Hospital and Daniel Stewart's Hospital.
Today, these have become the independent schools of Mary Erskine, Stewart's Melville College and George Watson's College, which collectively generate an annual income of nearly £40m, according to the figures published by the Office of the Scottish Charities Regulator.
The Mary Erskine School, popularly known as Mary Erskine's, is an all-girls secondary school in Edinburgh which has a roll of around 700 pupils.
The school is linked with Stewart's Melville College, an all-boys independent secondary school located close by, which also has 700 pupils.
Fees are £8184 per year for day pupils and around £16,329 for boarders.
Former pupils of Stewart's Melville include Michael Boyd, artistic director of the Royal Shakespeare Company, the international rugby players Finlay Calder and David Wilkie, Olympic swimming gold medallist.
George Watson's College formally opened in 1741 with an initial roll of 11 boys. It now educates 2309 pupils and charged annual fees of up to £8481.
Notable former pupils include actor Gordon Kennedy, the rugby playing brothers Gavin and Scott Hastings, broadcaster and journalist Martha Kearney and politicians Malcolm Rifkind and David Steel.
Second on the list of educational charities with an income of £14.6m is Hutchesons' Educational Trust, which runs Hutchesons' Grammar School in Glasgow.
It was founded by the brothers George Hutcheson and Thomas Hutcheson in 1641 and was opened originally to teach orphans, starting with 12 boys on the roll.
Today, affectionately known as "Hutchie", the school fees are in excess of £8000 a year.
Notable alumni include novelist John Buchan and television presenter Carol Smillie.
Merchiston Castle School in Edinburgh, one of the country's few all-boys schools, which is listed by OSCR as having an income of more than £11m, dates from 1828.
Founded as a boys' boarding school and still a strong advocate of single-sex education, former pupils include Irvine Laidlaw, the Scottish businessman, John MacGregor, a UK Cabinet minister under Margaret Thatcher and Sir Peter Burt, former governor and chief executive of the Bank of Scotland.
Another famous school to feature on the list is Fettes College in Edinburgh with an income of more than £12m. A boarding and day school which schooled former Prime Minister Tony Blair, it has some 640 students with fees per term of £7442 for boarders and £5280 for day pupils.
An all-boys school until 1970, when female pupils were first admitted for the final year, Fettes has, since 1983, been co-educational.
Famous Old Fettesians include Sir David Murray, chairman of Rangers Football Club and Tilda Swinton, the actress.
While expanding on James Bond's backstory, Ian Fleming wrote in You Only Live Twice that the spy had attended Fettes College after having been removed from Eton.
While Fleming never claimed there was any other source for the name of Bond than James Bond an American ornithologist, there was a real life James Bond who did attend Fettes.
OSCR's Chief Executive Jane Ryder said the overall list provided a useful snapshot of the sector's major charities by income.
"We are increasingly publishing data gathered from charities' Annual and Monitoring Returns and adding to public awareness of charity activity and reporting in Scotland.
"We do not anticipate the list to change markedly over time, but it should prove to be a useful reference point as we move forward.
"It is worth reflecting on the fact that prior to the new legislation and the establishment of OSCR, it was difficult to gauge the scale and even the total number of active charities in Scotland."