What are the Upanishads?

What are the Upanishads and how many of them are available now?

The word Upanishad literally means 'sitting near devotedly', and brings the picture of a sincere devotee learning from his guru- or spiritual master. The great Sankaracharya would, however, describe the Upanishad as simply knowledge of God.
There are , in all, 108 Upanishads ranging in length from a few hundred to many thousands of words, some in prose and some in verse. Of these, sixteen Upanishads were recognised by Shankaracharya as authentic and authoritative. In his commentary on Vedanta Aphorisms, he included quotations from six Upanishads. On the other ten Upanishads, he wrote elaborate commentaries. It is these ten Upanishads which, partly on account of their intrinsic importance but mailnly, no doubt, because of Shankara's commentaries, have come to be regarded as principal Upanishads. These ten Upanishads that form one of the vital bases of Hinduism are Isa, Kena, Katha, Prasna, Mundaka, Mandukya, Chandogya, Brihadaranyaka, Aitareya and Taittiriya.

What is synthetic rubber ?

What is synthetic rubber ?

Synthetic rubber is made of certain kinds of hydrocrabons. Of these, butadine is the most important. These hydrocarbons are obtained from coal, crude petroleum and alcohol. By the end of the Second World War, the combined production of synthetic rubber by USA and Germany alone was almost equal to that of natural rubber. Synthetic rubber is more oil-resistant than natural rubber. In the international market, natural rubber is facing severe competition from synthetic rubber.

Why do leaves fall in autumn?

Why do leaves fall in autumn?

The green colour in the leaves is due to a pigment, chlorophyll, in the plant. In autumn, the leaves stop making this pigment, thus the leaves turn yellow. Every leaf has a large vein underneath which carries water for nourishing it. This soon becomes dry in a yellow leaf so that water no longer flows through it. Thus the leaf dies and its grip on the branches loosens. When a strong wind blows, it breaks the leaf's grip and thus the leaves fall off in autumn.

Why do bees buzz?

Why do bees buzz?

The buzzing, sound is only caused by rapid fluttering of the bees'wings. The wings of the bees work like that of an electric fan. In hot weather, bees even carry water drops and spray droplets on their hives with their wings to cool it.

Why a pin-prick hurts?

Why a pin-prick hurts?

Human body is covered with skin. This skin is made up of several layers. Beneath the outermost layer are found millions of very small points. These are connected to a number of little threads called nerves. When the skin is pressed upon or touched, the nerves communicate the sensation to the brain. Thus the skin with the little nerves provides us with one of the five senses - "touch". If a pin goes into the outer layer and touches one of these little points, the touch becomes "pain"