Do not look for rest in any pleasure, because you were not created for pleasure: you were created for spiritual JOY. And if you do not know the difference between pleasure and spiritual joy you have not yet begun to live.
Life in this world is full of pain. But pain, which is the contrary of pleasure, is not necessarily the contrary of happiness or of joy. Because spiritual joy flowers in the full expansion of freedom that reaches out without obstacle to its supreme object, fulfilling itself in the perfect activity of disinterested love for which it was created.
Pleasure, which is selfish, suffers from everything that deprives us of some good we want to savor for our own sakes. Pleasure is restrained and killed by pain and suffering.
Spiritual joy ignores suffering or laughs at it or even exploits it to purify itself of its greatest obstacle, selfishness. True joy is found in the perfect willing of what we were made to will: in the intense and supple and free movement of our will rejoicing in what is good not merely for us but in Itself.
Joy, in so far as it is true, is above pain and does not feel pain. And that is why it laughs at pain and rejoices in confounding pain.
So it is a very sad thing when contemplatives look for little more than pleasure in their contemplation. That means that they will waste time and exhaust themselves in harmful efforts to avoid aridity, difficulty and pain—as if these things were evils. They lose their peace. And seeking pleasure in their prayer they make themselves almost incapable of joy.
From Thomas Merton, “New Seeds of Contemplation”