Although the history of the origin of the use of the concept and meaning of "good" are diverse, the notable discussions of Plato and Aristotle on this subject have been of significant historical effect. The first references that are seen in Plato's The Republic to the Form of the Good are within the conversation between Glaucon and Socrates (454c–d). When trying to answer such difficult questions pertaining to the definition of justice, Plato identifies that we should not "introduce every form of difference and sameness in nature" instead we must focus on "the one form of sameness and difference that was relevant to the particular ways of life themselves” which is the form of the Good. This form is the basis for understanding all other forms, it is what allows us to understand everything else. Through the conversation between Socrates and Glaucon (508a–c) Plato analogizes the form of the Good with the sun as it is what allows us to see things. Here, Plato describes how the sun allows for sight. But he makes a very important distinction, "sun is not sight" but it is "the cause of sight itself". As the sun is in the visible realm, the form of Good is in the intelligible realm. It is "what gives truth to the things known and the power to know to the knower". It is not only the "cause of knowledge and truth, it is also an object of knowledge".