Among the proofs of the existence of a divine power is this: that things are often known by their opposites. Were it not for darkness, light could not be sensed. Were it not for death, life could not be known. If ignorance did not exist, knowledge would not be a reality. It is necessary that each should exist in order that the other should have reality. Night and day must be in order that each may be distinguished. Night itself is an indication and evidence of day which follows, and day itself indicates the coming night. Unless night were a reality, there could not be day. Were it not for death, there could be no life. Things are known by their opposites.
Therefore, our weakness is an evidence that there is might; our ignorance proves the reality of knowledge; our need is an indication of supply and wealth. Were it not for wealth, this need would not exist; were it not for knowledge, ignorance would be unknown; were it not for power, there would be no impotence. In other words, demand and supply is the law, and undoubtedly all virtues have a center and source. That source is God, from Whom all these bounties emanate.
(‘Abdu’l-Bahá, The Promulgation of Universal Peace, p. 82-83)
For the break of the morn of divine guidance must needs follow the darkness of the night of error. For this reason, in all chronicles and traditions reference hath been made unto these things, namely that iniquity shall cover the surface of the earth and darkness shall envelop mankind.
(Bahá’u’lláh, The Kitáb-i-Iqan, p. 31-32)
If there was no wrong how would you recognize the right? If it were not for sin how would you appreciate virtue? If evil deeds were unknown how could you commend good actions? If sickness did not exist how would you understand health? Evil is non-existent; it is the absence of good; sickness is the loss of health; poverty the lack of riches. When wealth disappears you are poor; you look within the treasure box but find nothing there. Without knowledge there is ignorance; therefore ignorance is simply the lack of knowledge. Death is the absence of life. Therefore on the one hand we have existence; on the other, nonexistence, negation or absence of existence. Briefly; the journey of the soul is necessary.
(‘Abdu’l-Bahá, Foundations of World Unity, p. 77)
The very fact that the reality of phenomena is limited well indicates that there must needs be an unlimited reality, for were there no unlimited, or infinite, reality in life, the finite being of objects would be inconceivable. To make it plainer for you, if there were no wealth in the world, you would not have poverty. If there were no light in the world, you could not conceive of darkness, for we know things philosophically by their antitheses. We know, for example, that poverty is the lack of wealth. Where there is no knowledge, there is no ignorance. What is ignorance? It is the absence of knowledge. Therefore, our limited existence is a conclusive proof that there is an unlimited reality, and this is a shining proof and evident argument. Many are the proofs concerning this matter, but there is not time to go into the subject further.
(‘Abdu’l-Bahá, The Promulgation of Universal Peace, p. 424)
Were it not for the cold, how would the heat of Thy words prevail, O Expounder of the worlds? Were it not for calamity, how would the sun of Thy patience shine, O Light of the worlds?
(Bahá’u’lláh, Fire Tablet, Bahá’í Prayers, p. 217)