“I suppose the picture-habit (which I seem to have) is as bad as the morphine or whiskey one—and it does cost,” wrote Isabella Stewart Gardner to Bernard Berenson, Gardner’s trusted art advisor who brokered some of her most important treasures.

Off the Wall, a brand-new exhibition on view through Aug 15, not only strives to highlight the fruits of this picture habit in a way that they haven’t been seen before but to remind us that her collection (and therefore her museum) was born not out of a selfish desire to own art, but out of deep philanthropic ambition.

Gardner said in 1917, 14 years after the opening of her museum, “Years ago I decided that the greatest need in our Country was Art … We were a very young country and had very few opportunities of seeing beautiful things, works of art … So I determined to make it my life’s work if I could.” In her will, she stated that “[The Museum will be held in trust] for the education and enjoyment of the public forever.”

It was also stipulated in her will that the permanent collection could not be significantly altered. Should the museum’s trustees “at any time change the general disposition or arrangement of any articles which shall have been placed in the first, second, and third stories,” the museum and all of its belongings would be sold and the proceeds donated to Harvard.

This stipulation is the reason Off the Wall is being called a once-in-a-lifetime exhibition: Roof repairs have temporarily closed the second floor, and due to the nature of the museum (and the will), the art cannot simply be shuffled around and re-hung elsewhere. Rather than boxing up the second floor artwork and keeping it out of view, 25 works of art were chosen for the exhibition where they are being seen up close and personal and under ideal lighting conditions. Taking nothing away from Gardner’s eye, many of the pieces in her museum are not lit to their best potential and some are hung in places where it can be a challenge to get a good look.

A painting of Gardner herself greets you as you enter the exhibition: Isabella Stewart Gardner in Venice by Anders Zorn. It shows Gardner re-entering a room, having just been out on the terrace, inviting her guests to come watch the fireworks. Despite having seen this painting dozens of times before, its power never registered with me quite like this; that’s when I knew that Off the Wall was going to be unmissable.

Standing before the painting with curator Christina Nielsen, we marveled at the boldness of the red and the green paint. She pointed out to me that the doors Gardner is bursting through are mirrored, reflecting her hands and making her reach appear infinite. Her figure is rather like a flame, echoing Gardner’s luminous and zesty personality. In its usual home in the Short Gallery, furniture makes it impossible to look closely at the painting, and the honeydew green walls make it seem more demure.

Next, Rembrandt’s Self-Portrait, Aged 23 hangs at eye level. It is a painting that I always stop at for a few extra seconds, mindful of how it was almost taken from us 16 years ago during the infamous heist (the thieves removed it from the wall, but, for whatever reason, left it behind). Just like the Zorn painting of Gardner, we have never been able to gaze at the Rembrandt face-to-face.

Nielsen told me that even she was still noticing new things about the painting, like the bluish-green felt rim of his hat. She invited me to look at his eyes, which have always felt dark and piercing. Not so: At this proximity, the white, blue, and green of his eyes are unmistakable. Under this perfect lighting, the artwork doesn’t just look good, but it appears to have undergone a complete restoration.

In the next room, which features Italian and Spanish art, Michelangelo’s Pietà hangs next to Raphael’s Procession of Pope Sylvester I, both of which are easy to miss in their usual places. Fra Angelico’s stunning The Death and Assumption of the Virgin is a work that I can’t be sure I’ve even seen at the Gardner Museum before, the colors and details of which are astounding.

For Gardner aficionados, Off the Wall offers a chance to see these works as we’ve never seen them before and likely never will again. For greener visitors to the museum, I can’t think of a better way to become newly acquainted with these works: It is an immensely satisfying, even moving, tribute to Gardner and her vision.

OFF THE WALL: GARDNER AND HER MASTERPIECES. THROUGH 8.15 AT THE ISABELLA STEWART GARDNER MUSEUM, 25 EVANS WAY, BOSTON. OFFTHEWALL.GARDNERMUSEUM.ORG