People become superstitious because of tokens and signs which they make up themselves
A prejudice may often give an individual the feeling of strength and confidence – it can be considered as a type of affordable sedative
The majority of people can be described a superstitious: they believe in tokens and signs – a set of conditional rules, which are considered to be protective against a variety of troubles. A black cat running across your way is considered a very bad token in Russia. If a person holds on to a button and spits three times over the left shoulder, trouble will not hit him or her. When someone dies, family members cover all mirrors in the house with cloths for several days not to see the evil eye there. As a rule, people do not even think how superstitious they can be and they do such actions unconsciously, as if it is an absolutely normal thing to do. 
In ancient times, a ring on a finger used to be considered a talisman, the significance and the power of which was changing in a combination with a precious stone of different shape and color. Craftsmen used to engrave rings with magic drawings and signs. It was believed that rings were magic objects, in which specters lived. There was a special burial ritual with many tribes: people had to remove all rings from the fingers of a deceased person, not to let specters hold the person’s soul.
Modern people know only one function of the rings: a ring is believe to be an essential item in wedding ceremonies. The roots of the custom start in Ancient Rome, when people discovered that a circle was a wonderful symbol of eternal love. The Greeks were the first people who started wearing wedding rings on the fourth finger. That was the best choice to make: scientists determined later that the vein in the fourth finger – vena amoris – ends directly on the heart.
The belief in the magic power of trees appeared in Ancient Egypt. Egyptians were the first to wear wooden charms on the neck: different kinds of trees were possessing special energetic qualities. Our ancestors eventually started worshipping trees, thinking that trees were gods’ homes. Touching a tree was compared to touching the divine. The tradition was broken 2005 years ago, when Jesus was crucified on a wooden cross. In Russia, when people do not want to jinx themselves, they spit three times over the left shoulder and knock on a wooden item (that can be a door, a desk, etc) three times as well.
It is generally believed in Russia that a broken mirror brings misfortune. The story of this prejudice is ridiculous. Mirrors were first produced in the 15th century in Venice. Wealthy people made the token up in order to make their servants handle mirrors carefully.
Thirteen is considered to be the unlucky number all over the world. The combination of this number with Friday is considered to be a disaster. It has been documented that the number of various injuries and traumas increases on such days. It is not ruled out, though, that such a mystery occurs not because of the unlucky number, but because of people themselves, whose increased superstitious concerns manifest themselves in critical situations and troubles.
According to a Scandinavian version, which appeared long before the formation of Christianity, 12 happy gods were sitting at table in a palace, eating dinner. The 13th god appeared all of a sudden and started a flight, in which one of the gods was killed. A Christian version says that the belief in the fatal power of this number is explained with the Lord’s Last Supper with 12 apostles: someone was destined to die in the group of 13 people.
Spilling salt has been considered a very bad token for a very simple reason. Salt was used to keep food fresh, when refrigerators were not invented. Spilling salt on the ground implied hunger because food would go bad.
Psychoanalysts of all times explain such a variety of religions and beliefs with the human need to believe “at least in something.” A lot of scientists, however, can see a lot of positive things in superstitiousness. A prejudice may often give an individual the feeling of strength and confidence and a possibility to control events. It can be considered as a type of affordable sedative.
Read the original in Russian: (Translated by: Dmitry Sudakov)