This is one of the best psalms to teach children. It also bookends well with Isaiah chapter 40. With a little tweaking, any kid could memorize it, although there is the hurdle obstacle in verses 19-22 which might need explaining.
The psalm is about God's presence, especially His presence in the life of the believer. For God, "the night shineth like the day." This statement sounds so paradoxical at first. One is tempted to spiritualize it away and say yes, in my times of darkness God is with me. This true, yet the verse does get one thinking about God as Light, God as actually dispersing darkness. His very essence is the complete presence of light. In God is no darkness or shadow or shading! One finds one's self thinking of the verse in the book of Revelation that states there is no Sun in the Eternal City because God will be our light!
God's presence is everywhere. He knows when we sit and when we stand. He knows our thoughts before we thinking them. He knows our lives before it begins and after it ends. Before we are "curiously wrought in the lowest parts of the earth" and in the darkest part of Sheol. In addition, "curiously wrought" hints at the expertise of workmanship. We are God's handiwork, strangely and mysteriously made.
To ponder God's Presence before us, in us, around us, ahead of us, outside of us, and far from us, is a difficult endeavor. It is too complicated, too intense, too deep and too high for human mind to understand.
1O lord, thou hast searched me, and known me.
2Thou knowest my downsitting and mine uprising, thou understandest my thought afar off.
3Thou compassest my path and my lying down, and art acquainted with all my ways.
4For there is not a word in my tongue, but, lo, O LORD, thou knowest it altogether.
5Thou hast beset me behind and before, and laid thine hand upon me.
6Such knowledge is too wonderful for me; it is high, I cannot attain unto it.
7Whither shall I go from thy spirit? or whither shall I flee from thy presence?
8If I ascend up into heaven, thou art there: if I make my bed in hell, behold, thou art there.
9If I take the wings of the morning, and dwell in the uttermost parts of the sea;
10Even there shall thy hand lead me, and thy right hand shall hold me.
11If I say, Surely the darkness shall cover me; even the night shall be light about me.
12Yea, the darkness hideth not from thee; but the night shineth as the day: the darkness and the light are both alike to thee.
13For thou hast possessed my reins: thou hast covered me in my mother's womb.
14I will praise thee; for I am fearfully and wonderfully made: marvellous are thy works; and that my soul knoweth right well.
15My substance was not hid from thee, when I was made in secret, and curiously wrought in the lowest parts of the earth.
16Thine 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.
17How precious also are thy thoughts unto me, O God! how great is the sum of them!
18If I should count them, they are more in number than the sand: when I awake, I am still with thee.
19Surely thou wilt slay the wicked, O God: depart from me therefore, ye bloody men.
20For they speak against thee wickedly, and thine enemies take thy name in vain.
21Do not I hate them, O LORD, that hate thee? and am not I grieved with those that rise up against thee?
22I hate them with perfect hatred: I count them mine enemies.
23Search me, O God, and know my heart: try me, and know my thoughts:
24And see if there be any wicked way in me, and lead me in the way everlasting.