We jumped, all ten of us, knowing that four Canadian skydivers had died earlier that day in two separate incidents, when parachutes tangled or did not open or opened too late. Two of the dead men were our friends.

Still, we marveled at the view, hooted at our freedom and exulted in our success. It was my 400th jump, and I will remember it fondly as a happy event.

That night we talked, sometimes awkwardly, about our dead companions. Some of us cried. But there was also much laughter. And the next day, we jumped again.

And today and yesterday and all this week, to friends and family and co-workers, I have tried to explain why. Why do I jump out of airplanes? Why did I jump after hearing of the sudden deaths of my fellow skydivers? And why will I jump again?

I hear myself saying things like, "We all know the risks." Or, "Jumping out of an airplane is safer than driving down the highway." And, "When someone dies in a car crash, do you stop driving?"

But I know these answers aren't good enough. They are banal clichés made hollow by the fact of four broken bodies lying lifeless. As a skydiver, I must justify my participation in a sport that each year kills some of its participants. I must try to answer "Why?"

I first jumped from an airplane in 1975 when I was 18 years old. I did it because it looked daring and exciting and, perhaps, because I was neither daring nor exciting and I hoped this sport would make me so. But it did not. At first, it just made me scared.

I flailed and tumbled in freefall, stiff as a board and white with fear. Once, in panicked confusion, I steered my parachute into a tree. And though I spent lots of time and money, it seemed I would never master this sport.

But I kept jumping -- four jumps one year, five the next, 11 the following summer. And slowly, sometimes painfully, I started learning things -- how to fall controlled and stable, how to pick an exit point and land on target. How to turn and flip in freefall, how to move forward and back and up and down toward other jumpers in the sky. How to think and relax under stressful conditions.

And how to fly.

And I have continued learning. The skills are different now -- how to launch a four person formation from the step of a Cessna, or exit from a DC-3. How to dive straight down at 150 miles an hour, then use my body to brake and swoop and softly touch the arm of a friend.

And although these acts are uniquely thrilling and have given me pure moments of joy, I do not study them for their own sake. No, I study them because they teach me how to live.

Like many people, I am good at wearing masks and adopting attitudes to hide and shield my true self. But when the door opens at 10,000 feet, there is nowhere to hide.

Like many people, I am good at conveniently forgetting that myself, and all the people I know and love, must eventually perish. Jumping has taught me to fight and fear death, and to never forget that it's there. Like many people, I am good at concentrating on the mindless details that pass for normal -- like watching TV and getting the brakes fixed on my car. But when I jump, I forget all those endless inconsequentials. Instead I concentrate on the moment, and I remember how to live.

When I choose to step from an aircraft and then, 45 seconds later, to open my parachute, I control my destiny -- an opportunity often lacking in a 9-to-5 existence, and missing in a life forever threatened by disease or sudden highway death.

Skydiving has taught me that confronting fear (and I am always afraid before I jump) and risk is always important. Not only physical risk, with its rewarding shot of adrenalin, but also the importance of taking chances with the heart -- of risking friendship, love and laughter.

Though that weekend's tragedies flood me with remorse, they do not fill me with regret. Though I mourn the loss of my skydiving companions, I will not stop celebrating life.

Next weekend, I will try to keep learning. And I will jump again.