Aristoteles, Theophrastus, Plinius, and Dioscorides are the men of mark who raised botany and plant-learning out of their infancy and gave them a youthful vigour. They placed the method of learning, on its right basis. Instead of imagining what was true, and then collecting and studying plants to prove the correctness of the imagined notion, they began in the opposite direction. They strove to learn and discover facts,—truths, and then reasoned upon them. Ignorant people, and those men who have the minds of children, always like their opinions and ideas better than facts, and especially if the facts will not fit in with their notions. Such people do not know how hard it is to find out the truth in nature, how difficult it is for finite man to comprehend infinite wisdom. This was as true formerly as it is now, and hence the method of learning, taught by the earlier of those great men, was opposed to the understandings of the majority of their fellow men. They troubled the complacent ignorance of the day, and were therefore persecuted. Like brave men, they did not care for persecution, knowing that they did not deserve the wicked charges brought against them; they persevered, and not only enjoyed life much more than their opponents, but led good and useful lives. The works of these men were studied by all the learned, during fifteen hundred years and more; they were the text-books of science during what are called the dark or middle ages, and although now out of date, they were the good seeds of knowledge, sown in difficulty, in those early days. Aristoteles, Theophrastus, and Plinius were not only botanists, but naturalists in every sense, and the first named is especially celebrated as a student of and writer upon animals; he was a great zoologist. Theophrastus knew much about geology, and so did Plinius. These men, then, brought the science of botany out of its childhood, and saw it partly on its way through its youth; they had removed it beyond the fanciful ideas and strange notions of the earliest writers on the subject, and had begun to classify plants, and to study the relations of plants to surrounding nature, and to the wants of man. Chemistry and the use of the microscope were unknown, and therefore progress in the necessary direction could not be made at that time of the world.