“A letter always seemed to me like immortality because it is the mind alone without corporeal friend,” wrote Emily Dickinson. This treasure trove of letters captures minds throughout history, from presidents to pop stars to paupers. The sense of intimacy conveyed is often startlingly raw, taking us into the writers’ deepest desires and fears, and elucidating the complexities of the mind.

Here is an eclectic mix of love letters (the most poignant being to lost loved ones); fan letters (and a beautiful reply from Iggy Pop to a distressed young fan advising her to “take a deep breath and do whatever you must to survive”); job application letters (one from Leonardo da Vinci written in the 15th century); and rejection letters (some dismissing work that became hugely successful – one, rejecting Fawlty Towers, should buoy the heart of any aspirant scriptwriter).

The fierce urge to communicate is captured not only with pen on paper. One letter is imprinted into a clay tablet dating back to the 14th century BC. Another ancient one was discovered etched in a layer of birch bark. Then there is the desperate message carved into a coconut shell by John F Kennedy, stranded on the Solomon Islands in 1943, which resulted in his rescue.

These “time capsules”, as the compiler Shaun Usher describes the letters, are showcased in an aesthetic delight of a book, with many facsimiles of original documents reproduced, transporting us back to moments in the past and bringing them to life in evocative detail. Many duplicates beautifully convey the peculiar power of handwriting, threatened with extinction in the digitised age.

“I am writing this letter to let you know how real I am,” explained the author Kurt Vonnegut in 1973 to the head of a school board who had ordered copies of his books to be burned in the school’s furnace. A desire for justice blazes from many of the finest letters, eloquently expressing the most incandescent emotions, from rage to love.

The letters capture not only the intimately personal but also the pivotal political moments of history. In an 1865 letter, freed slave Jourdon Anderson responds to his former master’s request that he return to the plantation, speaking of the injustice of “making us toil for you for generations without recompense”. Here, writing becomes a righting of the wrongs of history from voices hitherto silenced – unforgettable voices filled with a defiant assertion of life and humanity that pulses through the pages.

Letters of Note is published by Canongate (£16.99). Click here to buy it for £13.93