05/19/2015 12:43 EDT | Updated 05/19/2016 05:59 EDT

'Authentic image of Shakespeare,' part of 400-year-old botany book, historian says

It's William Shakespeare as you've never seen him, according to a British expert who says he's identified the only illustration of the famed English poet and playwright made while he was alive.

"This is Shakespeare, age 33, drawn from life, in the prime of life," botanist and historian Mark Griffiths is quoted as saying in England's Country Life magazine. "This is what he looked like."

- AUDIO | The Science of Shakespeare

Griffiths says he made the discovery while researching The Herball — a 400-year-old volume on plants written by hearbalist and botanist John Gerard — namely by deciphering the identities of four men on the book's cover.

Three of the four could be identified as Gerard himself, Flemish botanist Rembert Dodoens, and Queen Elizabeth's chief minister Lord Burghley. The fourth figure was a bearded man, dressed as a Roman and wearing a poet's laurel wreath.

Like the others, Griffiths says his identify was "coded" in the plants and symbols around him.

"We have never, until now, had a demonstrably authentic image of Shakespeare that was created in his lifetime and identified as such by the artist," says Griffiths, "and that's exactly what we have here on the title page of The Herball."

There are only two known authentic likenesses of Shakespeare, but both were created after his death.

- One appears on the First Folio edition of his dramatic works.

- The other is a 17th century bust on Shakespeare's memorial at Trinity Church Stratford in Stratford-upon-Avon. 

A number of paintings appearing to depict The Bard have surfaced over the years, but critics have largely denounced them.

Anticipating skeptics

Griffiths's claim is quite extraordinary and he's worked for years to counter anticipated skeptics.

Edward Wilson, emeritus fellow of Worcester College, Oxford, told BBC News that he and Griffiths spent five years consulting with scholars of Latin and Shakespeare before going public with the discovery.

"We do not think anyone is going to dispute this at all," Wilson said.