Note that pohja is a more archaic form of pohjoinen meaning "north". In everyday language today, pohja means "bottom", but it originally meant both "bottom" and "north", because the two were considered to be synonymous with each other, i.e. that in the indigenous Finnish religious and cultural beliefs, and language, the "north" was considered to be the "bottom" and the "below", and was connected to the concept of a river flowing from this world into the underworld, i.e. the realm into which certain parts of our soul go upon death, or during trace, dreams etc. This same river also flows across the sky, where it is known as the linnunrata (one of my other websites is called "Languages of Linnunrata"), linnunrata meaning "path of the bird", which the ancient Finns saw the physical form of which as being the Milky Way. This "Cosmic River" is not only connected to the more metaphysical elements of the soul and spirit, but is also connected to the physical manifestation of the soul, which is water, and to the movement of water between the heavenly realms and the earth, and the cycle of that "water" and certain parts of the soul, back through the earth, the plants, and then back to the heavenly realms in terms of water evaporation and the sprouting of plants and other life etc.