Nothing can be truly understood if it is looked at from one side only. Everything which appears to us in one condition was quite different in earlier times; only by relating the present to the past can it be understood. Similarly, if you do not look beyond the physical world of the senses, you will never understand illness, or the mission of evil.
Source: Rudolf Steiner – GA 95 – At the Gates of Spiritual Science – Lecture VIII: Good and Evil. Individual Karmic Questions. – Stuttgart, 29th August 1906