What are the importance of using microscope to a biologist?

You obviously would be able to see things that you would not be able to see with the naked eye. Biologists study "life" and more importantly, microscopic aspects of life. Without the aids of microscopes, people today would still think that "miasma's" caused illnesses and that bacteria was simply fiction. Doctors would still be administering Mercury to patients (to induce violent vomiting) while penicillin would have never been discovered!