O Lord, thou hast searched me, and known me.
God is omniscient - He knows everything about every single one of us.
Thou knowest my downsitting and mine uprising, Thou understandest my thought afar off.
He knows everything we do, and He knows our thoughts even before we think them.
Thou compassest my path and my lying down, and art acquainted with all my ways.
He keeps a constant watch of us. Nothing of our ways are hidden from Him.
For there is not a word in my tongue, but, lo, O Lord, Thou knowest it altogether.
Before we say a single thing, He knows all about it - every word in the past, present and future.
Thou hast beset me behind and before, and laid Thine hand upon me.
His knowledge of us is so incredibly intricate that He can guard behind us and before us.
Forever and always His hand is protectively on us.
Such knowledge is too wonderful for me; it is high, I cannot attain unto it.
God's infinite knowledge is too much for our minds to comprehend, it is far beyond our capacity to understand. It is absolutely wonderful, greater than anything else we could know.
Whither shall I go from Thy spirit? or whither shall I flee from Thy presence?
God is omnipresent. We cannot go anywhere to hide from His presence.
If I ascend up into heaven, Thou art there: if I make my bed in hell, behold, Thou art there.
Going to heaven cannot take us away from God, and neither can making our bed in hell - we cannot get away from His presence.
If I take the wings of the morning, and dwell in the uttermost parts of the sea;
Even there shall Thy hand lead me, and Thy right hand shall hold me.
Even if we could travel at the speed of light (the wings of the morning are said to be an allusion to the rays of the morning sun), we would find the Lord there leading us and holding us with His hand.
If I say, Surely the darkness shall cover me; even the night shall be light about me.
Yea, the darkness hideth not from Thee; but the night shineth as the day: the darkness and the light are both alike to Thee.
Night cannot shut out God's presence; darkness is not dark to God, there is no difference between day and night, to Him - He can see even through the darkest night (unlike our human eyes which require light to see).
For Thou hast possessed my reins: Thou hast covered me in my mother's womb.
His power and skill are incomparable - He formed every part of us, inside and out. He wove all our body parts together to make them just so.
I will praise Thee; for I am fearfully and wonderfully made: marvellous are Thy works; and that my soul knoweth right well.
The human body is so complex, so intricately designed, it can do nothing but cause us to praise God. It is beautiful and wonderful and marvellous, and our souls know it without a doubt.
My substance was not hid from Thee, when I was made in secret, and curiously wrought in the lowest parts of the earth.
God knows us through and through from the very beginning and while we were in the womb, we were made - we could never just come to be by some accident.
Thine eyes did see my substance, yet being unperfect; and in Thy book all my members were written, which in continuance were fashioned, when as yet there was none of them.
Even before the different parts of our bodies grew (ie. from the moment of conception), the eyes of God could see us - God is eternal, He didn't need us to be a born human to be able to see us, He knew us when we were just a few cells with no arms or legs or even a head! And He fashioned each and every part of us.
How precious also are Thy thoughts unto me, O God! how great is the sum of them!
If I should count them, they are more in number than the sand: when I awake, I am still with Thee....
God thought about us and planned us very carefully, which should be precious to us; such minute attention to detail is not to be taken for granted. Those thoughts are spoken of as being present also - God did not just create us and then leave us to flounder. He continues to watch over us and have His hand on us continually - His thoughts of us are innumerable.
Search me, O God, and know my heart: try me, and know my thoughts:
And see if there be any wicked way in me, and lead me in the way everlasting.
This should be our constant prayer - for God to thoroughly search us and know our hearts. To carefully test and know our thoughts and expose those things that are not holy or pure - the wickedness of our hearts and thoughts need to be confessed and forsaken. Having God lead us in His way is the only way to walk before Him in purity and holiness.
(Psalms 139:1-18, 23-24)