We find a mighty drive in the animal kingdom that’s independent of sense organs. If one brings a foreign pair of butterflies to Germany and releases the male in Frankfurt and the female say in Magdeburg, the two will reunite without fail. They do this with special organs that are even finer than sense organs.
If we meet a total stranger whom we feel a great sympathy for, as happens between man and wife and also between friends, then this is a sign that these people belong together and that they have soul organs that tell them this and bring them together.
Source: Rudolf Steiner – Ga 266 – From the Contents of Esoteric Classes – Berlin, April 18, 1906