Ekadashi, or Ekadasi Vrat, is observed on the eleventh day of a fortnight in a Hindu lunar calendar. The day is dedicated to Lord Vishnu and many devotees undertake Upvaas or fasting on the day.
Ekadasi is a Sanskrit word, which means 'the eleventh'. It refers to the eleventh day of a fortnight belonging to a lunar month. There are two fortnights in a lunar month—the bright and the dark. So, Ekadasi occurs twice in a month, in the bright fortnight and the dark fortnight.
The Ekadasi observance is an astrological phenomenon and it is observed due to this relation we have with some of the planets in the system. The entire personality of ours is tremendously influenced by the movement of planets. There is no use imagining that the planets are above our heads. They are everywhere. There is a relative movement of planets among which the earth is one. The movement of one thing in relation to another is a relative movement. There is no planet which is static. Even the sun is not ultimately static. The whole solar system is moving and rushing towards some huge star, which is eighty million times larger and brighter than the sun, whose light has not yet reached us, as astronomers tell us. Each planet tells upon our system and we cannot get rid of the influence of theirs as long as we are in this planet, of which we are a part. The gravitational pull of planets has an influence on us.
In the Rig-veda, the sun is identified with the soul of the universe as well as the soul of the individual. The different limbs of our body and different parts of our system are supposed to be influenced by different planets. The sun is capable of influencing the entire being.
Ekadasi is particularly relevant to this relation of moon and mind. You will find that, when you go deep into the study of astronomy, you have nothing in your body except some planetary influences! We are made up of planetary forces and there is nothing independent to call our own. One part belongs to one planet and another part to another planet. If each planet claims its part, you will disintegrate. The moon influences the mind in its orbital relative movement with reference to other planets and us.
How, is Ekadasi related to the movement of moon and mind? We have certain centres called Chakras in the body. The Chakras are nothing but energy-centres which whirl in some direction as water whirls in a river. Chakra is a wheel or circular motion. They move in a spiral shape. They are not physical; but psycho-physical and psychological. These Chakras are neither in the mind nor in the body; they are in the astral body. The moon's influence physically on the body has an influence on the Chakras, which tells upon the mind ultimately. The mind moves through these Chakras. The passage of the mind is through these Chakras, up and down. When this operation takes place consciously, it is called Yoga; When done unconsciously by the mind, it is just influence. When the moon waxes or wanes, the mind is vehemently influenced. So people who are not normal in their minds become very bad on the full-moon and new-moon days. You cannot see the moon's influence on the earth because it is solid, but it can be seen on the ocean which is liquid. The moon influences the whole earth, but its influence is visible on the large body of waters in the sea. This happens due to the twofold pressure of the relation of the earth and moon. The sun influences the moon and the moon influences the earth. When the influence occurs automatically, we are instruments in the hands of Nature. When it is done consciously, we are said to practise Yoga.
Fast and meditation! What connection have they? There is really no intrinsic connection between fast and meditation, but there is some advantage in keeping the body light and the stomach free from excessive metabolic function. When the stomach is given the duty of digestion, doctors will tell you, the blood circulation is accelerated towards the digestive organs, on account of which blood circulation to the head gets decreased after food is taken and so you feel sleepy and the thinking faculty practically ceases to function. Hence, there is no advantage in giving the physical system work on days you want to do Yogic practice. Thus, Ekadasi has also a spiritual significance.