- Did Shakespeare use more than his genius to write plays?
- Evidence of cannabis found in four pipes from playwright's garden, say scientists
- Scientist: Bard may have made "cryptic reference" to cannabis in a sonnet
London (CNN)Was playwright William Shakespeare stoned when he penned masterpieces like "Hamlet" and "A Midsummer Night's Dream"?
New correspondence published in the South African Journal of Science highlights how an analysis of residue found in early 17th-century tobacco pipes excavated in Stratford-upon-Avon, central England, found indications of cannabis and nicotine. The report, which was first published in 2001, said that several of the pipes came from Shakespeare's garden.
A kind of cocaine derived from coca leaves was also found in two samples -- although neither of those were from the playwright's property.
The report did not claim to have proof that the Bard smoked cannabis or even that the pipes found in his garden belonged to him.
But author Professor Francis Thackeray, from the Evolutionary Studies Institute at University of the Witwatersrand in Johannesburg, South Africa, still speculates that cannabis could have been a source of inspiration for the Bard.
In this month's journal, he references a line from Shakespeare's Sonnet 76 that mentions "invention in a noted weed."
He told CNN via email Monday: "I think that Shakespeare was playing with words and (it) is probably a cryptic reference to cannabis."
Shakespeare could have enjoyed "the noted weed" for creative writing because it had mind-stimulating properties, he added.
If true, Shakespeare would join a long and illustrious list of writers from Byron to Hunter S. Thompson who have been inspired by drugs.
Thackeray originally carried out the analysis with fellow scientists Nicholas van der Merwe of the University of Cape Town and Inspector Tommy van der Merwe at the South African Police narcotics laboratory.
They used a technique known as gas chromatography mass spectrometry (GCMS) on pipe bowls and stems they loaned from the Shakespeare Birthplace Trust in Stratford-upon-Avon.
The study included 24 pipe fragments: cannabis was indicated in eight samples -- four of which came from Shakespeare's garden -- nicotine in one sample, and "definite evidence" for Peruvian cocaine from coca leaves in two samples.
In Shakespeare's time, various plants were smoked in clay pipes.
In 1597, the botanist John Gerard described a number of different kinds of tobacco in "Herbal," a botanical encyclopedia.
References include the tobacco plant, nicotania, which the explorer Sir Walter Raleigh is credited with bringing to England from Virginia.
The encyclopedia also describe a special kind of tobacco from Peru -- "the henbane of Peru" -- which is likely to be cocaine derived from smoking coca leaves, according to Thackeray.
Another explorer, Sir Francis Drake could have brought coca leaves to England after visiting Peru in 1597, notes the botanical encyclopedia.
Shakespeare additionally wrote about "compounds strange," in Sonnet 76, which may have been a reference to cocaine, said Thackeray in his email to CNN.
Cannabis had been condemned by the church before Shakespeare's time. "Writers who were explicit about Cannabis could have their books burnt," Thackeray added.