Magick teaches us that everything in the Universe is connected.
Correspondences are magickal associations.
They link herbs, animals, crystals, colors, lunar phases, and so on with specific energies, and thus with intended magickal results.
Correspondences are powerful keys that help to open specific doors, and thereby direct magickal energy in desired ways.
For those who have prior knowledge of magick, an understanding may be formed of why certain herbs, candle colors, and so on are used in the spells.
They may also understand why it is recommended that some spells be cast on particular days or during specified phases of the Moon.
If you have no understanding of these things, you can nonetheless make use of magickal correspondences by simply following the directions for the spells.
Names of deities are ancient Words of Power, so we invoke gods and goddesses to boost the magickal power of our spells.
Different deities have dominion over different things, so we invoke them in accord with the intent of our spells.
If you have studied mythology, you may understand why this god or that goddess is called upon in a spell.
If you know nothing about mythology, you can still access of the power of invocation by following spell directions.