Agathos Daimon means “good spirit” and is a religious observance held on the second day of each lunar month, immediately following the Noumenia. It is the third celebration of a trio of household monthly observances. A good spirit usually refers to a type of divine being that is less powerful than a God, is personal to each family, and can bring the family good luck, protection, or some type of assistance. Household spirits are usually seen as either snakes or as a young man with a horn of plenty in hand.

More about this spirit can be found at The Powers That Be:

• Agathos
• Agathodaemon

Some celebrate the Agathos Diamon by pouring a libation to the spirit and asking for his continued blessings on the family. If there is something in particular that your family wishes help with, give an additional offering to your family’s protective spirit. Although we know we can always approach the Gods directly, the Agathoi Diamones are seen to be helpful intermediaries between the Gods and man.

The second day of every Athenian month was also a sacred day, devoted to the Agathos Daimon (good spirit). The name daimon does not mean the evil demon of modern Christianity, (although it did have a negative form, called the kakodaimon), but was thought to be an aspect of Zeus, as Zeus Ktesios, Charitodotes, and Epikarpios, titles as giver of increase and joy.

Agathos Daimon is most often represented in the form of a snake, a symbol of healing. However the daimon is also a function of one’s being, a characteristic inherently neither good nor bad. The philosopher Sokratēs talks of his own daimon as a small voice which speaks to him and warns him to refrain from certain actions.

Hence, one prays for a good daimon, an eudaimon, and goodness from the gods for the coming month and also for the favor of father Zeus as Agathos Daimon.

• One must be on good terms with it. ~Burkert.
• The daimon active about me I will always consciously put to rights with me by cultivating him according to my means. ~Pindar
• The great mind of Zeus steers the daimon of the men whom he loves. ~Pythagoras

Many modern Hellenes follow the practice of pouring a libation to their own Agathos Daimon on the second day of the lunar month. Possible prayers include the Orphic Hymn to the Daimon.

Thee, mighty-ruling, Dæmon dread, I call, mild Zeus, life-giving, and the source of all:
Great Zeus, much-wandering, terrible and strong, to whom revenge and tortures dire belong.
Mankind from thee, in plenteous wealth abound, when in their dwellings joyful thou art found;
Or pass through life afflicted and distressed, the needful means of bliss by thee suppressed.
‘Tis thine alone endowed with boundless might, to keep the keys of sorrow and delight.
O holy, blessed father, hear my prayer, disperse the seeds of life-consuming care;
With favoring mind the sacred rites attend, and grant my days a glorious, blessed end.

Aeschylus in the Suppliant Maidens says: “May Zeus grant that it go well with us. For Zeus’ desire is hard to trace: it shines everywhere, even in gloom, together with fortune obscure to mortal men.” Kleanthēs prays: “Lead me, O Zeus, and thou O Destiny” and also, “If so it pleases the Gods, so let it be.”

Agathos Daimon is also associated with Dionysos, especially with His gift of wine. A feast was often closed with a small drink of unmixed wine, called either Agathos Daimon or Zeus Soter (savior), as though supplicating the god that they may do nothing indecent or have too strong a desire for the drinking, and may receive from it all that is noble and salutary.

Also, whenever you see a snake, give a prayer to Agathos Daimon and even pour a libation. In Hellenistic and Roman times, family ritual areas were often decorated by snakes.

Source: Hellenion