I think most everyone knows the Celtic-inspired Samhain that runs concurrently with Halloween, and shares many of the same features - but have you ever heard of the Ancient Roman holiday Lemuria? This observance occurred in May - but here's an interesting thing... it is very likely connected with All Saint's Day, which, of course, is the day following Halloween, or All Hallow's Eve.
You see, the Catholic Church originally observed All Saints Day on May 13 , altering it to November 1 by Pope Gregory III in 835 to commemorate the building of an oratory to house St. Peter's relics in Rome. The original date in May was the final day of the Roman festival of Lemuria, which involves dealing with one's ancestors. Several other Roman customs coincide with later Christian holidays, and it isn't difficult to imagine that the early Christians - who did not exist in a vacuum but sprang up from the culture in which they lived - attached their meanings to the holidays and customs that were already familiar to them, just as we tend to do today. I also tend to believe that moving it to that date, so near the also-known harvest customs of the Celts is why many Celtic customs have grown attached to the date.
But back to Lemuria - for the Romans, Lemuria was a three day festival when each household would exorcise itself of any malevolent ancestors (lemures) still hanging about and to honor the friendly spirits (lares) living there peacably. This was an important duty of the head of the household throughout the year, who was tasked with honoring the household spirits daily through prayer and offerings of food and drink, but at this time of year, it was time to clean spiritual house, so to speak.
The means to do so was to appease the spirits through offerings and ritual in order to encourage them to leave. Romans believed that spirits were peers and should be treated as such - shown respect, but not deference, and while they could not be compelled to do anything, they were willing to negotiate terms. Many religious practices involved promising to do something in exchange for favors - and fulfillment of promises made in order to ensure future good fortune.
A brief explanation of the rite of Lemuria is that the head of the household rises at midnight and walks the house barefoot (the dead were buried with 'feet unfettered' - so the head of household is meeting the spirits on their own terms) and spits mouthfuls of black beans behind him, crying, "‘With these beans I redeem me and mine". The spirts are said to take the offering of beans and go - or not. The head of household then bangs on metal gongs, saying, "Ancestral spirits, depart!" to frighten off those that refused the offering of beans. Finally, offerings are made to the friendly household spirits that are supposed to be there - a sort of very early 'trick or treat', where treats are offered to the spirits in order to avoid unfriendly tricks.
Ovid, in his Fasti, describes the ritual of Lemuria thus and goes on to explain its origin as coming from Romulus and Remus - and even shares why it's considered unlucky to marry in May:
"When Hesperus, the Evening Star, has shown his lovely face
Three times, from that day, and the defeated stars fled Phoebus,
It will be the ancient sacred rites of the Lemuria,
When we make offerings to the voiceless spirits.
The year was once shorter, the pious rites of purification, februa,
Were unknown, nor were you, two-faced Janus, leader of the months:
Yet they still brought gifts owed to the ashes of the dead,
The grandson paid respects to his buried grandfather’s tomb.
It was May month, named for our ancestors (maiores),
And a relic of the old custom still continues.
When midnight comes, lending silence to sleep,
And all the dogs and hedgerow birds are quiet,
He who remembers ancient rites, and fears the gods,
Rises (no fetters binding his two feet)
And makes the sign with thumb and closed fingers,
Lest an insubstantial shade meets him in the silence.
After cleansing his hands in spring water,
He turns and first taking some black beans,
Throws them with averted face: saying, while throwing:
‘With these beans I throw I redeem me and mine.’
He says this nine times without looking back: the shade
Is thought to gather the beans, and follow behind, unseen.
Again he touches water, and sounds the Temesan bronze,
And asks the spirit to leave his house.
When nine times he’s cried: ‘Ancestral spirit, depart,’
He looks back, and believes the sacred rite’s fulfilled.
Why the day’s so called, and the origin of the name,
Escapes me: that’s for some god to discover.
Mercury, son of the Pleiad, explain it to me, by your
Potent wand: you’ve often seen Stygian Jove’s halls.
The caduceus-bearer came, at my prayer. Learn then,
The reason for the name: the god himself revealed it.
When Romulus had sunk his brother’s spirit in the grave,
And justice was done to the over-hasty Remus,
The wretched Faustulus, and Acca with streaming hair,
Sprinkled the calcined bones with their tears.
Then at twilight they returned home grieving,
And flung themselves on the hard couch, just as it lay.
The bloodstained ghost of Remus seemed to stand
By the bed, speaking these words in a faint murmur:
‘Behold, I who was half, the other part of your care,
See what I am, and know what I was once!
If the birds had signalled the throne was mine,
I might have been highest, ruling over the people,
Now I’m an empty phantom, gliding from the fire:
That is what remains of Remus’ form!
Ah, where is Mars, my father? If you once spoke
The truth, it was he who sent us the she-wolf’s teats.
The rash hand of a citizen undid what the wolf saved.
O how gentle she was in comparison!
Savage Celer, wounded, may you yield your cruel spirit,
And bloodstained as I am, sink beneath the earth.
My brother never wished it: his love equals mine:
He offered, at my death, all he could, his tears.
Beg him by your weeping, by your nurturing,
To signal a day of celebration in my honour.’
They stretched out their arms at this, longing to embrace him,
But the fleeting shade escaped their clutching hands.
When the phantom fleeing dispelled their sleep,
They both told the king of his brother’s words.
Romulus, complying, called that day the Remuria,
When reverence is paid our buried ancestors.
Over time the harsh consonant at the beginning
Of the name, was altered into a soft one:
And soon the silent spirits were called Lemures too:
That’s the meaning of the word, that’s its force.
And the ancients closed the temples on these days,
As you see them shut still at the season of the dead.
It’s a time when it’s not suitable for widows or virgins
To wed: she who marries then won’t live long.
And if you attend to proverbs, then, for that reason too,
People say unlucky women wed in the month of May.
Though these three festivals fall at the same time,
They are not observed on three consecutive days."