The topic of this thesis is Plato's metaphor of the divided line, especially its significance for the philosophy of science. Its ontological, epistemological and ethical character will also be presented. The aim of the work is to study The Republic, focusing on the metaphor of the line, the Sun and the cave, showing interpretations and its significance for Plato's philosophy. It is about the analysis and synthesis of the original philosophical text and the presentation of the opinions of various philosophers on this topic. The metaphor of the line speaks of the separation of the line into four unequal parts, each of which corresponds to its objects of knowledge and the type of cognitive power of the soul. There are many interpretations of this metaphor, for example the question about the dualism of worlds or the degree of cognition and the transcendence of the idea of good. Plato's philosophy of science is reflected in the metaphor of the line, which we can see in his conception of astronomy and hypotheses. General questions related to his philosophy of science will also be presented, such as whether Plato advocated scientific realism or instrumentalism. The variety of debates that his philosophy of science has stimulated give an insight into its significance for the whole of science