“This material world is the world of duality, and we cannot understand happiness without distress or distress without happiness. This is therefore called the relative world. For instance, there may be fireworks going on, and this may be happiness for someone but distress for us. Some people are thinking that these: fireworks are very enjoyable, and we are thinking that they are very inconvenient. That is the material world. On one side there is happiness, and on the other side there is distress. Both happiness and distress are actually illusions. In summer, water is happiness, but in winter it is distress. The water is the same, but at one time it brings happiness and at another time it brings distress. When a son is born, he brings happiness, but when he dies, he brings distress. In either case, the son is the same.
Spiritual happiness is above these Dualities. In the material world, one minus one equals zero, but in the spiritual world, one minus one equals one. That is called advaya-jnana. There is no duality in the spiritual world. One plus one equals one, and one minus one equals one. If we love Kṛṣṇa, that love will not be destroyed as love is in the material world. In the material world, a servant serves the master as long as the servant is pleased and as long as the master is pleased. The servant is pleased as long as the master pays, and the master is pleased as long as the servant renders good service. However, in the spiritual world, if the servant cannot serve under certain conditions, the master is still pleased. And if the master does not pay, the servant is also pleased. That is called oneness, absolute. A guru may have hundreds of disciples, hundreds of servants, but he doesn’t have to pay them. They are serving out of spiritual love, and the guru is teaching without receiving a salary. This is a spiritual relationship. There are no cheaters and cheated in such a relationship. Similarly, in the material world we experience that fighting is just the opposite of loving, but in God the fighting propensity and the loving propensity are one and the same. That is the meaning of “absolute”. We learn from the Vedic scriptures that when the so-called enemies of God are killed by God, they attain liberation.”
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “The Science of Self-Realization”, Page 341