Plato is unable to tell us exactly what the Form of The Good is, but he does tell us that it is the source of intelligibility and of our capacity to know.
According to Plato, the Forms were in close relation with one another, ascending a hierarchal pyramid, with the 'illusions' or material objects at the base of it. In this system, there is a clear correlation between the 'goodness' of the quality and it's position in the chart: i.e. Higher up in the chart equals closer to the Ultimate Form. Plato has used this system of 'Forms' to express and emphasise his belief that the Form of the Good- or the representative metaphor in the Cave analogy; The Sun- is the ultimate standard of reality- the one idea that makes all other ideas, or judgements, of the mind possible. The Form of The Good illuminates and looks down upon all of the other Forms and provides them with their value. In his philosophy, Plato held the concepts of Justice, Wisdom and Courage in high esteem, as he believed they possess a high level of 'Goodness' within them; they appear close to the epitome of the pyramid. As an example, Plato had contended that 'Justice' is the "quality of the soul" in which all selfish temptations of men are set aside to consider a 'general' benefit. In this way, Plato considers 'Goodness', in this example as having the definition of leading a simplistic and almost selfless and dutiful existence.
As with the other Forms, Goodness is something we have never seen perfectly exemplified in the physical world, but nevertheless we have all experienced actions that we can innately or instinctively distinguish as being 'good' deeds. Plato would say that we are able to recognise their Goodness as a cause of our understanding of how they correspond to our intuitive knowledge of the Form of The Good, which is in existence in