According to Plato's philosophy, the Form of the Good is considered to be eternal and unchanging. It exists independently of the physical world and is not subject to the limitations of time, space, or perception. Plato believed that the Forms, including the Form of the Good, have a transcendent existence separate from the material realm. These Forms are the ultimate reality and serve as the foundation for the sensible world we perceive.

In Plato's view, the Forms are perfect and immutable, providing a standard of truth and goodness against which the imperfect and transient objects of the physical world are measured. The Form of the Good is the highest and most fundamental of these Forms, representing the ultimate source of knowledge, beauty, and moral value. It is the ultimate archetype that illuminates and gives meaning to all other forms.

Therefore, according to Plato's philosophy, the Form of the Good always exists as an eternal and unchanging reality, serving as a guiding principle for understanding the nature of truth, goodness, and the ultimate purpose of human existence.