In fact the law of karma is the most consoling law there is. Just as it is true that nothing exists without a cause, so it is equally true that nothing existing remains without its effects. I may be born in poverty and misery; my abilities may be very limited; yet whatever I do must produce its effect, and whatever I accomplish now, by way of industry or moral activity, will certainly have its effect in later lives. If it depresses me to think that I have deserved my present destiny, it may equally cheer me to know that I can frame my future destiny myself. Anyone who really takes this law into his thinking and feeling will soon realise what a sense of power and of security he has gained. We do not have to understand the law in all its details; that becomes possible only at the higher stages of clairvoyant knowledge. Much more important is it that we should look at the world in the light of this law and live in accordance with it. If we do this conscientiously over a period of years, the law will of its own accord become part of our feelings. We verify the truth of the law by applying it.
Source: GA 95 – At the Gates of Spiritual Science – Lecture VI – Stuttgart 27th August 1906