They conceived the bond of union in the concrete form of eating together.

As language improved and passing events were recorded in speech and in the mind, the faculty of memory was perhaps concurrently developed.

Then man began to realise the insecurity of his life, the dangers and misfortunes to which he was subject, the periodical failure or irregularity of the supply of food, and the imminent risks of death.

Memory of the past made him apprehensive for the future, and holding that every event was the result of an act of volition, he began to assume an attitude either of veneration, gratitude, or fear towards the strongest of the beings by whom he thought his destinies were controlled--the sun, moon, sky, wind and rain, the ocean and great rivers, high mountains and trees, and the most important animals of his environment, whether they destroyed or assisted to preserve his life.

The ideas of propitiation, atonement and purification were then imparted to the sacrifice, and it became an offering to a god.