Reality is something totally different from what we perceive with our senses. Things that we see in the real World the Objects of sensory perceptions are
mutably and perishable. Time is an important factor in this regard and Objects change over time and perish over time. These are the images of Archetypal of the Ideas. These Ideas are
immutable and imperishable. Thus, they will never change. Ideas only exists in our mindset, i.e. in our mind. the Objects of the real world or simply instantiations of these ideas.
From the view of Computer Science Ideas are Classes and Objects are their Instances (Object-oriented Programming). Thus, one need to distinguish between Classes and their Instances of these Classes. Instances are the Objects of the real World, while Classes are the Ideas that are only existent in our mindset or Hard-Disc.