So in medical terms, if a single disease process can explain all the symptoms present, then it is pretty safe to make the conclusion that that disease is most likely to be causing all the problems. Rather then looking for multiple causes for the symptoms, I just go ahead and do tests that confirm the presence of that single disease. More often than not I am correct, and treatment need not be delayed while waiting for more test results. Occasionally, rarely, I am incorrect. This is a good way to do things when time and money are factors for a client and patient.

Extrapolating this concept, there has been a series of coincidences in my life, a chain of unlikely events that has led to my becoming a veterinarian. This story is almost as preposterous as the so-called butterfly effect, which postulates that when a butterfly flutters its wings in one part of the world, it can cause a hurricane on the other side of the world. In other words, no matter how small a change in someone's life, it could totally change life's outcome.

My story starts with one of my earliest memories. It's a vivid memory indeed - not like a dream, more like a defining moment.

I was about five years old and living in Kwun Tong. On the way home after school every day I would take the same route up a steep set of steps. At the top of the steps I would always turn left and head straight home.

But one day, for some inexplicable reason, I turned right instead. I was usually afraid to go to the right because an old beggar lived on the side of the road there and he really scared me. My father would use this old man as an example to teach me to study and work hard, threatening that if I did not I could end up on the streets like him.

But for some reason I wasn't worried about the old beggar that day and headed along the road in that direction.

There was a church along the road, with a circular driveway around a pretty fountain. The gardens on the side of the driveway were well tended and there were many different-coloured daisies growing. It was late afternoon and the sun was dipping low on the horizon, casting an orange-yellow hue on everything like in an old photograph.

As a child I didn't appreciate this idyllic scene. What caught my attention was a black cat sitting on the edge of the fountain grooming itself.

It stopped grooming when it realised it was being watched and stared back at me unflinchingly. It didn't run away. So I approached it slowly. I was surprised that it didn't run away and I thought at the time that maybe it felt safe because it was at a church and protected by a higher power.

I shrugged this off as an acceptable explanation and got really close, close enough to touch it. It still didn't run away. I went ahead and tentatively reached out a hand to pat it. Although it was nervous, it let me do it. After a minute or so, I figured that it might even let me pick it up. But when I tried, it struggled and scratched me. I naturally pushed the cat away from me, and I remember vividly that it had a limp as it ran away into the shadows of nearby shrubs.

For a long time I felt very guilty that I might have hurt the cat, and I worried about its survival. For me it was a defining moment, a butterfly effect that led me to make decisions that ended up with my becoming a veterinarian.

It probably wasn't divine intervention, and in hindsight I don't think I was responsible for the cat's injury. But since I am a sceptic and don't believe in coincidences, I truly think this moment has been festering in my subconscious all my life. It seems as if I am destined to help sick animals as penance for hurting that little cat.