For British artist David Hockney, it only took one sentence to trigger debate on an arguably indispensable part of his profession.

"All the works here were made by the artist himself, personally," reads the line, which is said to be on the wall of his latest exhibition at London's Royal Academy of the Arts.

It was initially reported to be a jab at fellow artist Damien Hirst, the reputed "bad boy" of contemporary art, who uses assistants to produce much of his work.

Hockney has since denied taking a personal swipe at Hirst, who is perhaps best known for submerging a shark in formaldehyde and encrusting a skull with diamonds.

Still, the 74-year-old's comments have scraped up questions about art, assistants and the nagging issue of authorship.

Assistants, or the artists behind the artists, have helped produce artwork for hundreds of years. They're often the craftspeople behind the scenes; stretching canvases, painting backgrounds, assembling installations and more.

"It's been very common for centuries, if not for millennia," said Michelle Jacques, a curator at the Art Gallery of Ontario.

Despite the extra hands, these works are usually attributed to a single artist on gallery pamphlets and promotional material. The question of who and how to credit remains one of the most irksome questions about the use of assistants.

Jacques noted that even Michelangelo, the Renaissance artist whose famous frescoes adorn the Sistine Chapel, had assistants help him paint backgrounds.

But he's just the tip of the brush, so to speak, as a countless number of artists such as Peter Paul Rubens and Rembrandt did -- and still do -- the same.

Most in the art world, including Jacques, argue there's nothing disingenuous about assisted work being attributed to a single artist, as long as the assistant's contribution remains minimal.

Hockney: 'The hand counts'

For Hockney, however, the issue of assistants seems to about honouring craftsmanship.

"It's an argument about the hand," he said in a widely circulated Radio Times interview. "I would say the hand counts…there are a whole school of artists who say it wouldn't."

It's a romantic assertion but flawed, notes a curator at the Ontario College of Art and Design. From the Renaissance and onwards, Charles Reeve points out that having and being an assistant is an understood part of the profession.

"Not only do most artists have assistants, but most artists who you've heard of, at some point in their career, have been assistants," he said.

The artist-assistant relationship, however, has been known to sour.

Look no further than Andy Warhol's New York studio "The Factory" for an example. Reeve notes that the pop-art pioneer, perhaps best known for his Campbell's soup can print, eventually drew the ire of many volunteers who felt they deserved more compensation or credit for helping to produce his work.

"When he died, there were legions of people who were extremely bitter for how they felt they had been treated," said Reeve, speaking in a phone interview from Toronto.

While scorned assistants are plentiful in the art world, Reeve notes that an artist can also be a positive force in an assistant's life. He named Canadian artist Jeff Wall, who's best known for his compelling photographic works, as someone who assumes the role of mentor.

"He chooses people who he thinks really have the potential to make it as artists on their own, then does what he can to help them along," said Reeve.

‘Art is not created in a vacuum'

German artist Martin Kippenberger once inadvertently addressed the artist-assistant relationship by ordering an assistant to make 51 paintings, which he then destroyed. The wrecked work was displayed next to full-size photographs of the original paintings.

Kippenberger's seemingly futile action is now viewed as a reflection on authorship and the idea of the artist as completely independent. By destroying the paintings, some believe he demonstrated just how complex those issues can be.

While having an assistant is almost an industry standard for high-profile artists, there are still some who produce work independent of any help.

In Austin Kleon's opinion, artists shouldn't be judged solely on whether or not all of their work is produced with their own hands.

"In some sense, art is always a collaboration -- an artist is always working with other artists," the author of "How to Steal Like an Artist" wrote in an email.

He's critical of the idea of any artist as completely independent. As an example, he pointed to films attributed to so-called auteur directors, who produced their work with the help of hundreds of people.

Expanding on the idea of art as collaboration, he added, "Whether they're borrowing influences, or turning their back on a tradition and trying to do something completely new – either way, art is not created in a vacuum."