You can't see it. There is no "proof" it exists, but the soul cannot be overestimated or over valued. Even if we gain the whole world, we cannot do so at the risk of harming our soul.
Is It Well With Your Soul?
February 2, 2009
The Letter to Diognetus, dating from approximately 125AD, is an early example of an "apology," a document defending the Christian faith addressed to a non-Christian.
Both the author and the person to whom it is addressed are unknown. But the insight we get into the character and reputation of early believers in Jesus is remarkable and very helpful. The following excerpt gives "flesh and bones" to the concept of the soul in a way that awakens gratitude for the God who made us in His image.
What the soul is in the body, Christians are in the world.
The soul is dispersed through all the members of the body, and Christians are scattered through all the cities of the world.
The soul dwells in the body, but does not belong to the body, and Christians dwell in the world, but do not belong to the world.
The soul, which is invisible, is kept under guard in the visible body; in the same way, Christians are recognised when they are in the world, but their religion remains unseen.
The flesh hates the soul and treats it as an enemy, even though it has suffered no wrong, because it is prevented from enjoying its pleasures; so too the world hates Christians, even though it suffers no wrong at their hands, because they range themselves against its pleasures.
The soul loves the flesh that hates it, and its members; in the same way, Christians love those who hate them.
The soul is shut up in the body, and yet itself holds the body together; while Christians are restrained in the world as in a prison, and yet themselves hold the world together.
The soul, which is immortal, is housed in a mortal dwelling; while Christians are settled among corruptible things, to wait for the incorruptibility that will be theirs in heaven.
The soul, when faring badly as to food and drink, grows better; so too Christians, when punished, day by day increase more and more.
It is to no less a post than this that God has ordered them, and they must not try to evade it.
Dear friend, I pray that you may enjoy good health and that all may go well with you, even at your soul is getting along well. 3 John 2