Mesa means table. There are sacred tables called altars or masks of the earth. Altars have an umbilicus or navel and have married the earth. They link the spiritual with the physical. They are places to prayer and reverence. There are many kinds of altars, church altars, community altars and altars associated with various rituals. There are different alters for different purposes. But we are speaking here of personal altars or home altars. An individual can gather spiritual resources and use them on their altar to draw power.
When working with altars make a sacred space. Altars can face toward any direction but the usual home altar faces east--this for devotion, illumination and spiritual seeking. These altars bring the sacred into your life. In the east are placed pictures of teachers, ascended masters, bowls of (holy) water, religious icons or any item that may draw spiritual power to you. Use seven white candles to the very front of your altar.
Briefly, the south holds your personal power objects, crystals, military metals, awards, and so on--ordinary things that bring you into consensus reality and which establish trust. Add items from your childhood if you like.
The west holds ancestral items, relics, sacrificial incense--any item that connects you with the dreamtime or your inner world. Include items that connect you with your ambitions or other wishes.
The north put loadstones, meteorites, lunar or solar icons, any small object an elder has given you. Here, are placed items that energize you as well as items that remind you of old age and the enfoldment of your spiritual path.
In the very center of your altar is a place that engages all four quadrants. East, south, west and north--these cogent zones of purpose lend power to this spot called "stamen and pistil" or "house of the hermaphrodite." It is in this powerful house where conversionary energies occur and bring magical shifts into circumstance.
Altars are moments of impeccability in the vast sweep of infinity. Oriented to the zenith of the celestial vault they are aligned with the forces of the cosmos. All objects placed on them draw power to the totality of the altar, and consequently, to you.