When it comes to defining eras in modern fashion, it’s tough to beat the late 1960s. From Yves Saint Laurent popularizing the trouser for women with his Le Smoking to Keith Richards upending menswear norms by pilfering from girlfriend Anita Pallenberg’s closet, fashion during the end of the ’60s was more revolution than evolution. And at the center of that revolution was the Summer of Love. During the summer of 1967, more than 100,000 flower children descended on San Francisco to celebrate peace, love, and freedom—united, however loosely, by music, wild fashion, drugs, and opposition to the Vietnam war. It was a genuinely optimistic moment. As Hunter S. Thompson wrote in Fear and Loathing in Las Vegas, “There was a fantastic universal sense that whatever we were doing was right, that we were winning…we were riding the crest of a high and beautiful wave.” This year marks the 50th anniversary of that high and beautiful wave, and to celebrate, Levi’s Vintage Clothing has released a 50th anniversary Summer of Love collection. Kicking off with an appearance at this year’s Monterey Pop Festival—basically the festival that created music festivals, and the place where Jimi Hendrix made his name after lighting his guitar on fire—Levi’s has brought back a lineup of some of its greatest 1960s hits, including painted “Crazy Legs” jeans, striped tees, and trucker jackets. We spoke with Levi’s Vintage Clothing head of design Paul O’Neill about what it was like to dip back into such a classic era. See more at Esquire.