Academician V. Vernadsky was always asking himself a question how science influenced the personality of a scientist. He believed that science was a factor elevating personal morals (ethics) and generosity. Vernadsky's 'hygiene of thought' purifies one's intellect and opens ideals for a scientist to aspire, but it doesn't mean to restrict scientific interest by professional boundaries. Vernadsky could combine it with the world outlook, to foster his attitude to science. According to Vernadsky, a genuine scientist must possess several qualities that foster the moral image of a scientist, such as courage, truthfulness, self-respect, duty and responsibility, freedom of thought. Vernadsky's distinguishes between social and professional responsibility. To produce a new piece of knowledge, a scientist elaborates and rethinks results of his predecessors and colleagues by his/her own, which causes specificity of relations within science, that is, between existing and new knowledge. Therefore, a scientific community must be convinced that scientific results are produced in compliance with methodological and technical criteria. This is an imperative for the existence of science as a social institute, because mutual trust is its self-regulation mechanism. Also, Vernadsky shows relationship of ethics with methodology and sociology of science. Methodology deals with methods and procedures of research, while ethics deals with its normative regulation. A scientist must be responsible for keeping up with methodological norms, as they have an ethical element. Scientific ethos as a set of norms and values, being passed through generations of scientists, becomes obligatory for a man of science.