Easter is the most important Christian celebration.  It commemorates the Resurrection of Jesus-Christ on the third day after his passion, as recounted in the Bible (New Testament).  The solemnity begins on Easter Sunday, indicating for the Catholics the end of fasting for the Lent, and lasts eight days (Easter week or the radiant week or the week of the eight Sundays).
The name Easter, derived from Greek and Latin, comes from the Hebrew “Pesach”, and is a Jewish festival commemorating the exodus from Egypt.  According to the Gospels, it is during this Jewish holiday that the Resurrection of Jesus took place which is why the name was given to designate the Christian feast.
The original Passover and the Christian feast of Easter are different.  The first commemorates, by a ritual meal called Passover, the exodus from Egypt.  The Christian feast is manifold as it commemorates the exodus from Egypt, the Eucharistic institution during the Easter meal, the crucifixion of Christ and his rest in the tomb for three days, his resurrecting passage from death to life, and the new creation inaugurated on the third day.

Calculating the date of Easter is a rather complex process that varies depending on the region of the globe where it is celebrated and on the calendar used.  In non orthodox European countries, Easter is celebrated on the first Sunday following the full moon of the spring equinox.  Easter Monday is also a statutory holiday in most countries of the Christian tradition as is Good Friday in certain countries.  Easter is considered the most significant Christian feast and brings important and very solemn church services, particularly in the orthodox tradition.   During the entire week, Orthodox Christians salute each other with the exclamation “Christ is resurrected!”, to which one answers “In truth, He is resurrected!”
From a symbolic understanding, a link exists between the resurrection of Christ and the victorious return of light in the spring.  This symbol is manifested in churches by the Easter candle lit up the night of Easter and present at each service until Lent of the following year.

Many pagan traditions celebrating the return of spring are linked to Easter. The Easter egg, symbol of the germination taking place at the beginning of spring, is the most traditional gift for Easter day.  Egg giving is a tradition dating back to antiquity.  Egyptians and Romans already were offering painted eggs to the mother goddess (Venus, Isis, etc) in the spring because they were a symbol of life and rebirth.  With the prohibition of egg consumption during Lent established by the Catholic church in the fourth century –unused eggs were decorated and given away as gifts. Nowadays, even with fasting not being as strictly followed, the tradition of giving out eggs, including chocolate ones, remains.  In Belgium and in the South-West of France it is the Easter bells that bring the Easter eggs.  A multitude of popular traditions have been created throughout Christian countries on the theme of the Easter egg, with eggs being decorated, painted, distributed or exchanged on Easter Sunday.

Omraam Mikhaël Aïvanhov, “Christmas and Easter in the initiatic tradition.”, pp. 98-99

“Jesus said, “I am the Resurrection and the Life.” Jesus rising from the dead is proof that we too can accelerate the process of Resurrection.  It comes to each one eventually.  But for it to work a transformation in our thinking, feeling and acting, we must make every effort to improve.  In the past, The Resurrection was part of the Initiatic Instruction in the Temples. Millions of beings have resuscitated: it is not necessary to die physically; there is no need for the tomb.
To resuscitate means that you no longer have the same weaknesses, the same vices and habits, the same illnesses, that your cells have become utterly pure, that they vibrate intensely.  All who live a very intense spiritual life are preparing their resurrection from the dead.”

Omraam Mikhaël Aïvanhov, “Christmas and Easter in the initiatic tradition.”, p.112 & 113

“Nature has put signs everywhere, indications to show us how to make the Resurrection occur in us.  When you meditate, you are a chrysalis shut up in your cocoon, preparing your metamorphosis.  If you have not yet transformed yourself into a butterfly, it is because your efforts were insufficient, you have been too busy with your affairs, like a caterpillar dragging along and eating all the leaves off the trees.  Then again you close yourself up in your cocoon and weave a few spiritual threads…but your affairs once more interrupt your work.  Each day you start again…and so on, until the day when finally you come out of the cocoon:  a butterfly! At that moment, you no longer want to destroy leaves, you feed only on nectar, that is, you draw on all that is most subtle in the heart and soul of men and women and have no desire to eat them or defile them.  Each being has something delicious, a bit of nectar inside, and if you make a habit of tasting this nectar, from then on you will always fly in the Light. […]

Tu Bishvat is a Jewish holiday in the rabbinic tradition. It is the “New Year of the Trees”, a celebration of the renewal of the land of Israel.

It occurs on the 15th day of the month of Shevat and falls on January 16th, 2014. It is indeed at this time of the year that the earliest flowering trees, particularly the almond trees, wake up from their winter sleep and begin a new blooming cycle.

The Tu Bishvat day is celebrated by eating fruits, particularly those mentioned in the Torah as a praise of the abundance of the Holy Land: grapes, figs, pomegranate, olives and dates.

That day reminds us of the passage in the Deuteronomy in which it is said that “man is a tree of the field” and invites us to meditate on the lessons that we can learn in our “double botani”.

Omraam Mikhaël Aïvanhov - Izvor Collection No. 209 Christmas and Easter in the Initiatic Tradition, IV

“Haven’t you seen that a tremendous event is taking place all round you, called a renewal?... One can feel that a new wave from the Cosmic ocean is breaking and in a short while the whole earth will be newly arrayed with flower, trees, birds. What splendid attire! It is the most extraordinary phenomenon of life, this regeneration and renewal.

Yes, except humans! Humans remain the same; they do not join the world’s renewal. They may sense something happening around them, but they do not let themselves be influenced. They must learn now to open the inner doors and windows so that the new life can penetrate and impregnate them!
That is the important thing I have to say to you this morning: it is too bad that this regeneration and renewal should be something in which only Nature takes part whilst humans remain concentrated on ancient things from the past and barely notice. You have to be free and disengaged to receive the new life with open arms.
…
There is an important work to be done, the work of renewal. Let other matters wait, put aside everything old and worn, and concentrate on the new life, enter into communication with the great current springing forth from the heart of the universe.”

Makar Sankranti – or Thai Pongal in Tamul – southern regions of India – is the only celebration based on the solar calendar: it takes place every year at the same date: January 14. The Sun, symbol of knowledge and of spiritual light, reverses its course. It moves North, from the tropic of Cancer to the tropic of Capricorn, which in Hindi is the crocodile tropic (makar). The half portion of the year when the sun moves southward is called a night of the Gods; when the sun moves northwards again, the period is called the day of the Gods. Makar Sankranti inaugurates the luminous half of the year. “Sankranti” designates the passing of a zodiacal sign into another. For the Hindus, the Sun is the symbol of knowledge, spiritual light and wisdom. Makar Sankranti means that we should turn our back to the darkness of illusion in which we live and begin to benefit from a new life originating from the living light shining more and more from within. As the Sun follows its course, grow purity, wisdom, knowledge should progressively grow within us..
The period of the solstice is particularly important. The first obligatory ritual is to bathe in the Ganges at dawn. There is a crowd; everyone – including the young ones- are bathing in the river: one must begin this “day of the Gods” with a fresh start.
In the Tamul tradition, the Thai Pongal festival lasts for several days during which the old clothes and fabrics are first burned, indicating the beginning of a new life. In both traditions, symbolic dishes of rice are prepared, shared and even distributed on the street.
Makar Sankranti is also an important harvest festival celebrated in different parts of India. This feast is also that of kites. In the bazaar, at every corner, street sellers offer paper lozenges of every color mounted on a bamboo frame. The sky is filled and children compete for their ability to make them fly higher and higher…

Omraam Mikhaël Aïvanhov - CW X "The splendour of Tipharet", p22

“The first thing to do is to realize how important the centre is and what great changes will begin to occur within you, even without your knowing it, as soon as you start to seek the centre. The nearer you get to the sun in spirit, soul and thought, with your heart and will, the nearer you will be to God for, on the physical plane, the sun is the symbol and the tangible, visible representative of the Deity. All those abstract, remote names by which men designate God: Source of Life, Creator of Heaven and Earth, Prime Cause, Almighty God, Universal Soul, Cosmic Intelligence… can all be summed up in the one concrete, familiar reality of the sun. Yes, the sun can be seen as the summary and synthesis of all those sublime, abstract ideas which are beyond our comprehension. The sun is the gateway, the physical link, the medium through which we can unite with the Lord.”