This is from one of Van Gogh's letters to his beloved brother Theo.

There’s the one who’s an idler through laziness and weakness of character, through the baseness of his nature; you may, if you think fit, take me for such a one.

Then there’s the other idler, the idler truly despite himself, who is gnawed inwardly by a great desire for action, who does nothing because he finds it impossible to do anything since he’s imprisoned in something, so to speak, because he doesn’t have what he would need to be productive, because the inevitability of circumstances is reducing him to this point. Such a person doesn’t always know himself what he could do, but he feels by instinct, I’m good for something, even so! I feel I have a raison d’être! I know that I could be a quite different man! For what then could I be of use, for what could I serve! There’s something within me, so what is it! That’s an entirely different idler; you may, if you think fit, take me for such a one.

In the springtime a bird in a cage knows very well that there’s something he’d be good for; he feels very clearly that there’s something to be done but he can’t do it; what it is he can’t clearly remember, and he has vague ideas and says to himself, ‘the others are building their nests and making their little ones and raising the brood’, and he bangs his head against the bars of his cage. And then the cage stays there and the bird is mad with suffering. ‘Look, there’s an idler’, says another passing bird — that fellow’s a sort of man of leisure. And yet the prisoner lives and doesn’t die; nothing of what’s going on within shows outside, he’s in good health, he’s rather cheerful in the sunshine. But then comes the season of migration. A bout of melancholy — but, say the children who look after him, he’s got everything that he needs in his cage, after all — but he looks at the sky outside, heavy with storm clouds, and within himself feels a rebellion against fate. I’m in a cage, I’m in a cage, and so I lack for nothing, you fools! Me, I have everything I need!

Ah, for pity’s sake, freedom, to be a bird like other birds!
An idle man like that resembles an idle bird like that. And it’s often impossible for men to do anything, prisoners in I don’t know what kind of horrible, horrible, very horrible cage. There is also, I know, release, belated release. A reputation ruined rightly or wrongly, poverty, inevitability of circumstances, misfortune; that creates prisoners.

You may not always be able to say what it is that confines, that immures, that seems to bury, and yet you feel I know not what bars, I know not what gates — walls. Is all that imaginary, a fantasy? I don’t think so; and then you ask yourself, Dear God, is this for long, is this for ever, is this for eternity?