Mnemosyne is the goddess of memory.
Her name is derived from
the same source as the word mnemonic, 
that being the Greek
word which means “remembrance, memory”.
Mnemosyne was usually
depicted as a mature woman with a full mane of luscious,
rich auburn hair. 
Mnemosyne was mostly regarded as a goddess
of memory and remembrance.
She is sometimes seen as
the goddess of words and language
as she invented them.
Her memory is so great that 
she remembers everything since
the beginning of time, making
her a minor goddess of time.
She is also the patron of poets and the goddess of sight and writing.
Since she is a daughter of Uranus and Gaia and
an elder Titaness, she is very powerful.
Specifically, she was considered one of the most powerful beings in her time.
As the Titaness of Memory,
she has absolute control and
divine authority over memories.
She did this for the dead,
allowing them to regain the memories of their past lives.
She may even have domain over recorded images
like video or photographs, objects of visual memory.
As the Titaness of Memory, 
she will
never forget anything and will always remember.
As the inventor of language and words,
she holds domain over both.
Like her sister Rhea,
Mnemosyne also presided over an oracle, thus
implying that she may also possess the power of foresight.
Like all Titans, Mnemosyne has the ability
to blast things hundreds of yards away
from herself with a yell or a wave of the hand.
As a Titanness, it is possible that Mnemosyne
also has the ability to incinerate any being
lesser than a god/Titan only by being present.
In the Underworld, Mnemosyne stood over a black pool
that was eventually named after her.
It is opposite to the River Lethe as it gives
people back their memories instead of making them forget.
Mnemosyne also presided over a pool in Hades,
counterpart to the river Lethe, according to
a series of 4th-century BC Greek funerary inscriptions
in dactylic hexameter.
Dead souls drank from Lethe
 so they would not remember their past lives
when reincarnated. 
In Orphism, the initiated were
taught to instead drink from the Mnemosyne, the river of memory,
which would stop the transmigration of the soul.
Although she was categorized as
one of the Titans in the Theogony, 
Mnemosyne did not
quite fit that distinction.
Titans were hardly
worshiped in Ancient Greece,
and were thought of as
so archaic as to belong to the ancient past.
They resembled historical figures more than anything else.
Mnemosyne, on the other hand, traditionally appeared
in the first few lines of many oral epic poems
—she appears in both the Iliad and the Odyssey, 
among others
—as the speaker called upon her aid in accurately
remembering and performing the poem he was about to recite.
Mnemosyne is thought to have been given
the distinction of “Titan” because memory was so important
and basic to the oral culture of the Greeks that
they deemed her one of the essential building blocks
of civilization in their creation myth.
Later, once
written literature overtook the oral recitation of
epics, Plato made reference in his Euthydemus to
the older tradition of invoking Mnemosyne.
The character
Socrates prepares to recount a story and says
“Consequently, like the poets, I must needs begin my
narrative with an invocation of the Muses and Mnemosyne”.
Aristophanes also harked back to the tradition in his
play Lysistrata 
when a drunken Spartan ambassador invokes
her name while prancing around pretending to be a bard
from times of yore. 
While not one of the most popular
divinities, Mnemosyne was the
subject of some minor worship
in Ancient Greece. 
Statues of her are mentioned in the
sanctuaries of other gods,
and she was often depicted
alongside her daughters the Muses.
She was also worshipped
in Lebadeia in Boeotia, at
Mount Helicon in Boeotia, and
in the cult of Asclepius.
Zeus, in a form of a mortal
shepherd, and Mnemosyne slept
together for nine consecutive
nights, thus conceiving the nine Muses.
Calliope - Calliope is the Muse of epic
poetry and and her name
means “she of a beautiful voice”.
She is believed to be
Homer's muse, the inspiration
of The Iliad and Odyssey.
Calliope also had two famous
sons, Orpheus and Linus,
by either Apollo or Oeagrus,
king of Thrace.
According to Hesiod, she was also
the wisest of the Muses,
as well as the eldest of the muses.
Kalliope is often
seen with a writing tablet in her hand.
At times,
she is depicted as carrying
a roll of paper or a book
or as wearing a gold crown.
Her symbols are a lyre, tablet and stylus.
 Clio
- She is often represented
with a parchment scroll
or a set of tablets
and is also known as the Proclaimer.
The name is from
the root κλέω/κλείω,
("recount" or "make famous").
'Clio' represents history
in some coined words:
cliometrics, cliodynamics. In
Classical times,
when the Muses were assigned
specific literary and
artistic spheres, Clio was
named Muse of history.
She has been credited with
introducing the phoenician alphabet
into Greece. She
had one son, Iakintos.
Some sources say she
was also the mother of Hymenaios.
 Her symbols are
an open scroll and a chest full of books.
Erato - The
Muse of love and erotic poetry.
 Her name is derived
from the Greek word
eros and means “desired, lovely”.
Most of the time
she is depicted playing
a kithara or a lyre,
but in some cases she is
shown with a wreath of myrtle and roses.
 Euterpe
- Euterpe is the Muse of music
and lyric poetry and her
name means “well pleasing”
and depicted holding a Double-Flute.
A few say
she invented the aulos or
double-flute,
though most mythographers credit Marsyas
with its invention.
She lay with the river god
Strymon and gave birth
to a son, Rhesus; during
the Trojan War,
Rhesus led a band of Thracians and
was killed by Diomedes.
Melpomene - Melpomene initially
the Muse of Chorus,
she then became the Muse
of Tragedy,
 for which she is best known now.
Her name was derived
from the Greek verb melpô
or melpomai meaning
"to celebrate with dance and
song." She is often
represented with a tragic
mask and wearing the cothurnus,
boots
traditionally worn by tragic actors.
Often, she also
holds a knife or club
in one hand and the
tragic mask in the other.
Polyhymnia - Polyhymnia is the muse of hymns and oratory.
She was in Greek mythology
the Muse of sacred poetry, sacred
hymn, dance, and eloquence as well
as agriculture and pantomime. Her name
comes from the Greek words
"poly" meaning "many" and "hymnos", which
means "praise". She is depicted
as very grumpy, pensive and meditative,
and often holding a finger to
her mouth, dressed in a long cloak
and veil and resting her elbow on a pillar.
Polyhymnia is also sometimes
credited as being the Muse of
geometry and meditation. She is the
only Muse who does not have a symbol.
Terpsichore - Terpsichore
is the Muse of dancing and choral songs.
Her name means
“delighting in dance,”
and she is sometimes
said to be the mother of
the Sirens by Achelous.
She is usually depicted
sitting down, holding a
lyre, accompanying the dancers' choirs with her music.
Her symbols are the lyre and plectrum.
 Thalia - Thalia is the muse of comedy
and idyllic poetry and her name means
“blooming, flourishing”.
According to pseudo-Apollodorus,
she and Apollo were the parents of the Corybantes.
There is also a Grace named Thalia,
though they are not the same.
Her symbol is a comical mask.
Urania - Her name means “heavenly, of heaven”.
Urania's symbols are a rod and a celestial globe.
Urania was said to be the first master of the horse Pegasus,
and also the one who saved him from the wrath of Zeus
after Bellerophon tried to use him to fly to Mt. Olympus.
