It is our consciousness that convinces us of our existence. Thoughts can only express consciousness, more or less as a tennis ball expresses roundness. Descartes, searching for the key to existence, thought it necessary for him to have an object to study. Consciousness, however, is not an object, but the subject of anything seen. Consciousness is the universal constant, irreducible to any other abstraction.
Happiness also is irreducible.
It is expressed in countless ways. We may experience happiness in the fulfillment of a long-cherished desire, or in release from suffering. Though most people identify their happiness with specific circumstances, it is a constant of life, underlying all our experiences. Sorrow is not such a constant. Happiness, on the other hand, is subtly, watchfully present even at times of great tragedy.