Fritz Grobe and Morten Hansen are guys you better keep an eye on. They move fast. They move sure. And you never know what might go down if you look away for just a nanosecond. In fact, by calling their performance company blink, they pretty much dare you to do just that — and can all but promise that, when you open your eyes, nothing will be the same.

Jugglers are like that, after all. Balls go up, balls go down, but they never stay still. As the guest artists at this weekend’s spring dance show by the Robinson Ballet Company, the members of blink hope to get you thinking about the notions behind the motions of juggling.

“A lot of our work is related to trying to answer the question of what exactly is juggling,” said Hansen, a physics major who switched to performing arts in college and has been juggling for about seven years. “Juggling is not exactly the most productive activity. So why are we driven to pursue this?”

“We want people to see that this is a part of our world. It has changed how we look at things,” says Grobe, who dropped out of a mathematics degree program at Yale to become a juggler. “Morty is the worst fidgeter in the world. The worst I ever met. He can’t sit still without seeing something to do. That’s how we see the world — in terms of manipulating something.”

Hansen waits for his turn to speak and adds: “Fritz has this amazing ability to sit still for a long time and come up with a trick that has a mathematical solidity to it.”

Hansen and Grobe (pronounced gro-bah) grew up about 10 minutes away from each other (in Bath and Brunswick, respectively), but didn’t meet until about seven years ago, when Hansen, who learned juggling from a book, saw Grobe performing. After that, they started juggling together and, in 1995, formed blink, which is based in Brunswick. Both have worked with Avner Eisenberg, the nationally known juggler-clown who lives on Peaks Island. Both have also worked with the renowned mime Tony Montanaro at his studio in South Paris.

Last year, blink gave 100 shows, and has performed in Scotland, England, and throughout the United States. In 1995, blink won the Dance Portland Choreography Showcase with its signature piece “Dysfunction,” catching the eye of Keith Robinson, co-artistic director at Robinson Ballet.

“I went `wow’ and they knocked my socks off,” says Robinson. “It was so technically clean, and you were mesmerized by what they did. They had easy movement, but there was amazing stuff going on.”

Trying to get actual descriptions of the work isn’t quite as easy, however. There are balls being juggled, perhaps some interaction with the audience, and balls being dropped. Yes, dropped. It’s not a planned thing, but, when it happens, it becomes part of the show.

“A lot of people watch juggling and feel a nervousness for the performer,” says Hansen, who can keep as many as 10 balls in the air at once. “A bunch of times in our show, we try to explore that. We’ll explore dropping and what that means in and of itself.”

“Sometimes it’s a lot more interesting to drop than to catch a ball,” says Grobe, who specializes in feats with diabolos, also known as Chinese yo-yos. “It creates a new situation. We practice several hours a day, and, obviously, we drop things. We are always striving to do it perfectly, but imperfection is a lot more interesting. Showing how we deal with problems is interesting.”

Grobe and Hansen say they have come to know each other’s moves with a high percentage of accurate anticipation. They practice both individually and as a twosome for several hours a day. Onstage, their goal is to get people to forget they are watching jugglers, and to go with the abstractions in patterns the two men create.

And of course, it works best if you don’t blink.

Blink will perform at the Robinson Ballet “Festival of Motion” 8 p.m. March 21, and 2 and 8 p.m. March 22 at Bangor High School’s Peakes Auditorium. For information, call 942-1990.