When Dr. Gabor Maté answered the telephone for an interview with the Georgia Straight, he was interrupted while reading Homer’s Odyssey, a Greek epic written almost 2,800 years ago.

“I’ve found in it the earliest mention I can think of of psychedelic substances being used as a healing or as a mood-altering modality,” he said. “They don’t identify it, but they learned it in Egypt and we know there was hemp in Egypt, so I suspect it was cannabis. Though Homer doesn’t say.”

For about 3,000 years, Maté emphasized, humans have consumed marijuana for a variety of reasons.

“My background is in medical practice and addictions, and I’ve seen marijuana used both ways,” he continued. “Then, of course, there is recreational use, which is perhaps no different from having a glass of wine.…Then there are some people who use it as a spiritual sacrament.”

Recreational, medical, spiritual, or as a symptom of addiction: “What is the dynamic behind the different uses of it?” Maté asked.

On October 13, the well-known physician and author of several books is scheduled to speak to that question during the International Cannabis Business Conference at the Hyatt Regency hotel in Vancouver.

Drawing on a decade of experience working as a physician in the Downtown Eastside’s low-income hotels—much of which is recounted in his 2009 book, In the Realm of Hungry Ghosts: Close Encounters With Addiction—Maté brings a unique perspective to drug-policy issues, one built on an open mind that understands the risks of drug use but also possible benefits, such as those of alternative therapies using ayahuasca.

“When somebody goes to a liquor store, you don’t know if they are buying wine to have a drink over dinner or whether they are buying it to get blasted because they are so miserable in their lives that they can’t stand how they feel,” he said. “The people who are worried about it [marijuana] being used addictively, they are quite right to be worried. But that’s not an argument for it to be illegal or more heavily controlled than other substances.”

With Parliament scheduled to table legislation to legalize recreational marijuana in the spring of 2017, Maté suggested lawmakers need to understand the larger issues behind addiction, such as emotional pain and unhappiness.

Another well-known name from Vancouver will present at the conference the following day, October 14.

In 2001, Donald MacPherson went to work for the city, drafting the “Four Pillars Drug Strategy”, a seminal policy document that emphasizes the roles of treatment and harm reduction in responding to addiction as a medical issue.

In a separate phone interview, MacPherson, now the executive director of the Canadian Drug Policy Coalition, said he plans to speak about Prime Minister Justin Trudeau’s process to legalize recreational marijuana.

“It’s a unique opportunity to reorganize an existing market,” he told the Straight. “All of the same dynamics will exist. There will be profit motives just like there is with the illegal market, and there will be tensions between public health and the public-health framework—of trying to identify and control various harms related to cannabis—and the industry, which, presumably, wants to increase or maximize profits.”

MacPherson said one of the greatest challenges the new Liberal government will face in legalizing and regulating recreational marijuana is to successfully snuff out the existing black market that has thrived for many decades.

He noted that this could take quite some time—years, at the very least. MacPherson suggested the trick will be to balance concerns for health and safety with market-friendly forces like convenience and low prices.

“This is an opportunity for industry, government, and the community to work together to create a really good system,” he said. “But the illegal market is not going to disappear overnight.”

Gabor Maté and Donald MacPherson will speak at the International Cannabis Business Conference, which takes place on October 13 and 14 at the Hyatt Regency Vancouver.