The first time I have ever been this sure

Today in biology my prof was being so inspirational, at least to me, that I was writing his full quotes in the margins of my notebook He was lecturing on the definition of the word species, he said the most wildly used definition is "a group of organisms that interbreed and produce viable and fertile offspring." He than went on to list a good twenty examples of why this definition does not always hold water. He than said, "In biology hard and fast rules are not needed, terms describe most but in no way all." He then told us not to obsess over the definitions believed to be true, they should not fascinate us. We should be fascinated at the exceptions to the rules and try and come up with our best explanation for them. He told us though that ultimately whatever new theories come around an organism will always be, "what it is and have the properties that it has." He then went on to say that he knew the lack of being able to truly define anything might bother, even scare some us, but ultimately it should free us. He said if it doesn't, "I hope you are just taking this class as a liberal study." I realized it did not bother me at all but it is in fact the reason I want to be a biologist. All the rules can bend, there is no "standard procedure." Being a biologist is actually about constant learning, not memorizing some information that someone else already learned. The whole goal of a biology is to prove the accepted theories false. In biology we can only disprove or fail to disprove a hypothesis, it is impossible to prove truth. Nothing is ever the answer it is only ever the best possible guess. Biology is not an exact science, and nothing about it will ever suffocate me.