I would boil down his basics to three orientations towards life: to see things as they are now, as we wish they were, and as they will one day be. Most art falls into one of these three basic life orientations.
We tend to look at things: as they are, as we wish they were, or as they will be. And we interpret from one of these three perspectives. The prophetic, as Heschel teaches us, tends to speak into the present from the future—so looks at what is, based on what it will be, and speaks from there. If we judge based just on what things are now, we tend to lack hope. If we judge based on what we wish things were, we can get a bit blinded, and deny current suffering (redemption is not possible if there is no suffering, as one great theologian taught). If we judge with a vision of what this will be, and speak into its present towards its future, we start to drawn things towards their destinies!
These categories are from Aristotle’s poetics. He felt art had these basic three orientations. But I would broaden it, to how we interpret life in general. I would put it:
So, we tend to interpret things from one of these focuses:
As they are, as they should be, and as they will be-prophets see backward from will be. Faith sees from the future into the present. It interprets based on vision of the destiny of the other. And speaks from that future space into its present to draw it towards that vision of wholeness.
 Yet, we each tend to see in one of these ways. These are different ways of interpreting life.
Faith gazes backwards from the future into the now.
We tend to interpret things by how they are, what we wish they were, or a vision of what they will be. This is true of art and life.
 Prophetic Optimism is not blind. It’s based on a vision of what we will one day be, and it speaks as if already true-which calls us forth to incarnate that vision.
Dialoguing with his book on art.

We tend to interpret things from one of these focuses:

As they are, as they should be, and as they will be-prophets see backward from will be. Yet, we each tend to see in one of these ways. These are different ways of interpreting life.

Faith gazes backwards from the future into the now.

We tend to interpret things by how they are, what we wish they were, or a vision of what they will be. This is true of art and life.

Prophetic Optimism is not blind. It’s based on a vision of what we will one day be, and it speaks as if already true-which calls us forth to incarnate that vision.

In dialogue with his book on art. The greeks had sort of a scientist’s look at art view, and it’s helpful in considering the components and overall orientations towards life and art. Worth a study at least! Enjoying re-reading this basic book on art and life. And considering its implications to how to live well.