Seneca, Moral Letters 58.5

But I now return to the subject which I promised to discuss for you, namely, how it is that Plato divides all existing things in six different ways. 
 
The first class of "that which exists" cannot be grasped by the sight or by the touch, or by any of the senses; but it can be grasped by the thought. Any generic conception, such as the generic idea "man," does not come within the range of the eyes; but "man" in particular does; as, for example, Cicero, Cato. The term "animal" is not seen; it is grasped by thought alone. A particular animal, however, is seen, for example, a horse, a dog. 
 
The second class of "things which exist," according to Plato, is that which is prominent and stands out above everything else; this, he says, exists in a pre-eminent degree. The word "poet" is used indiscriminately, for this term is applied to all writers of verse; but among the Greeks it has come to be the distinguishing mark of a single individual. You know that Homer is meant when you hear men say "the poet." What, then, is this preeminent Being? God, surely, one who is greater and more powerful than anyone else.
 
The third class is made up of those things which exist in the proper sense of the term; they are countless in number, but are situated beyond our sight. "What are these?" you ask. They are Plato's own furniture, so to speak; he calls them "ideas," and from them all visible things are created, and according to their pattern all things are fashioned. They are immortal, unchangeable, inviolable.
 
And this "idea," or rather, Plato's conception of it, is as follows: "The 'idea' is the everlasting pattern of those things which are created by nature." I shall explain this definition, in order to set the subject before you in a clearer light: Suppose that I wish to make a likeness of you; I possess in your own person the pattern of this picture, wherefrom my mind receives a certain outline, which it is to embody in its own handiwork. That outward appearance, then, which gives me instruction and guidance, this pattern for me to imitate, is the "idea." Such patterns, therefore, nature possesses in infinite number—of men, fish, trees, according to whose model everything that nature has to create is worked out. 
 
In the fourth place we shall put "form." And if you would know what "form" means, you must pay close attention, calling Plato, and not me, to account for the difficulty of the subject. However, we cannot make fine distinctions without encountering difficulties. A moment ago I made use of the artist as an illustration. When the artist desired to reproduce Vergil in colors he would gaze upon Vergil himself. The "idea" was Vergil's outward appearance, and this was the pattern of the intended work. That which the artist draws from this "idea" and has embodied in his own work, is the "form."
 
Do you ask me where the difference lies? The former is the pattern; while the latter is the shape taken from the pattern and embodied in the work. Our artist follows the one, but the other he creates. A statue has a certain external appearance; this external appearance of the statue is the "form." And the pattern itself has a certain external appearance, by gazing upon which the sculptor has fashioned his statue; this is the "idea." If you desire a further distinction, I will say that the "form" is in the artist's work, the "idea" outside his work, and not only outside it, but prior to it. 
 
The fifth class is made up of the things which exist in the usual sense of the term. These things are the first that have to do with us; here we have all such things as men, cattle, and things. 
 
In the sixth class goes all that which has a fictitious existence, like void, or time. 

—from Seneca, Moral Letters 58 

 
Once we make detailed distinctions, there may be weeping and the gnashing of teeth, and yet, as with so many frustrations, the practice can still do us a world of good. 
 
Now I do know many “scholars” who like to muck about with the technicalities because it makes them feel like big experts, but that should not be our concern. It will, however, always be necessary to isolate in which particular sense we are employing a term, and whether the expression is accordingly clear or unclear. 
 
So, when the salesman says he will do right by me, or the judge demands that I obey the law, or the priest insists he wants to save my soul, or the girl proclaims that she loves me, I must be on my guard. What precisely do they mean by what is right, or the law, or saving, or loving? I can avoid much later grief by discerning how our separate meanings were not in tune. 
 
I may mean it narrowly, and you may mean it broadly. I may see it more exactly, and you may see it more loosely. I may take it literally, and you may take it figuratively. We may, in the end, actually be speaking of two completely different things, only accidentally united by a word. 
 
This does not require us to condemn one another, or to engage in a fight; it only requires us to understand the respective senses of our definitions, and from there we might ultimately come to a common awareness. I remain convinced that the vast majority of human problems arise over hastily and sloppily delineated concepts. 
 
And when I say something “exists”, isn’t it important to clarify how I intend the word? It can’t really get more basic than the senses of being, can it? 
 
Even if I am not a follower of Plato in one or another matter, the exercise of distinction is never wasted, as long as it serves to refine comprehension, and thereby to inspire more worthy living. This letter is already tempting me to go on for far too long, so I’ll keep these six senses as brief as I can: 
 
I may speak of something “existing” in the sense that I possess a concept of it within my mind. Note how I am not grasping one or another particular, but rather apprehending a universal shared in common by many instances. 
 
I may speak of something “existing” in the sense that it is the perfection of a certain type or class, as when the classicist distinguishes between any old poet and the poet, Homer, or when musicians refer to some king in general and the King, Elvis. 
 
I may speak of something “existing” in the sense that the universal is itself a deeper reality, an absolute and unchanging “idea” from which all other instances receive their relative identities. This is the classic Platonic teaching of the subsistent reality to the intelligible realm, the models or archetypes of changing bodies. 
 
I may speak of something “existing” in the sense that the transcendent “idea” is instantiated or expressed in a specific “form”, as when an artist creates a work to reflect a deeper truth, goodness, and beauty. 
 
I may speak of something “existing” in the sense of a material and sensible individual case. For most of us, this is what we believe to be the most real, even as for the Platonist it is actually the least real, an imperfect duplicate. 
 
I may speak of something “existing” in the sense that it is hypothetical or a construct within my perception, as when I send a letter to Santa Claus, or refer to time and space as if they were somehow solid and immovable entities. 
 
If you bear with the argument for just a little longer, you will soon discover how and why this letter is asking us to reevaluate our assumptions about the “real” resting first in the objects of sense—while we surely begin with such impressions, it is the judgments of the mind that reveal the underlying essence, and so can best isolate the precious purpose to this life. 

—Reflection written in 5/2013