A few years ago I stumbled upon the Isha Upanishad. It is the shortest of all the Upanishads. Gandhi once called this the most important of all books. Here are a few of my favourite quotes....
It moves and It moves not. It is far and also It is near. It is within and also It is without all this. - Isha Upanishad
All manifestation is merely a modification of the One Supreme Whole .... The Whole therefore remains unaltered. - Isha Upanishad
All existence is in the Absolute; and whatever exists, must exist in It; - Isha Upanishad
In the light of true wisdom the phenomenal and the Absolute are inseparable. - Isha Upanishad
The indefinite term “That” is used in the Upanishads to designate the Invisible–Absolute, because no word or name can fully define It. - Isha Upanishad
OM! That (the Invisible–Absolute) is whole; whole is this (the visible phenomenal); from the Invisible Whole comes forth the visible whole. - Isha Upanishad
... the One Cosmic Existence shines through all things - Isha Upanishad
...so long as man believes himself to be separate from the Whole, he is helpless. - Isha Upanishad
That is the ocean, we are the drops. So long as the drop remains separate from the ocean, it is small and weak; - Isha Upanishad
That which comes out of the Infinite Whole must also be infinite; hence the Self is infinite. - Isha Upanishad
...there is no difference between the Self and God. They are one and the same. - Isha Upanishad
Transcending death means realizing the difference between body and Soul and identifying oneself with the Soul - Isha Upanishad
..when he sees all creatures within his true Self, then jealousy, grief and hatred vanish. He alone can love. - Isha Upanishad
He who sees all beings in his Self and his Self in all beings, he never suffers - Isha Upanishad
We must not divide our conception of the universe; for in dividing it, we have only fragmentary knowledge and we thus limit ourselves. -Isha Upanishad
.... behold the vast, radiant, subtle, ever–pure and spotless Self, the true basis of our existence. - Isha Upanishad
When a man sees God in all beings and all beings in God, and also God dwelling in his own Soul, how can he hate any living thing? - Isha Upanishad
He who perceives the Self everywhere never shrinks from anything, because through his higher consciousness he feels united with all life.
He who perceives all beings as the Self for him how can there be delusion or grief, when he sees this oneness (everywhere) ? Isha Upanishad
He who sees all beings in the Self and the Self in all beings, he never turns away from It - Isha Upanishad
It is the innermost Soul of all creatures & It is without as the essence of the whole external universe... Isha Upanishad
It is near to those who have the power to understand It, for It dwells in the heart of every one - Isha Upanishad
Source: http://www.yoga-age.com/upanishads/isha.html
Mohandas Karamchand Gandhi thought so highly of it that he remarked, "If all the Upanishads and all the other scriptures happened all of a sudden to be reduced to ashes, and if only the first verse in the Ishopanishad were left in the memory of the Hindus, Hinduism would live for ever."- Wiki