St. Ephraim the Syrian: Praise to the Incarnate God

Praise to the Lord 

Who took flesh for our salvation

Praise to Him Who descended to us in human form! Praise to the Invisible One who became visible for our sake! Praise to the Eternal One Who tasted death for us! Praise to the Mysterious One whom no mind can comprehend, and Who through His grace made Himself manifest by taking on flesh!
Blessed is He Whose good will brought Him to His mother’s womb and bosom, to be born and reared! Blessed is He Who partook of death and thus granted life to mankind.
Blessed is He Who made our flesh a dwelling place for His mysterious being. Blessed is He Who declared to us His mysteries in our own tongue.
Praise to Him Who liberated us, having been bound for our sake. Glory to Him Who is plenteous in mercy, Who has redeemed us without taking anything in return. Praise to the Judge Who accepted condemnation for our sake.
Let us worship Him Who has enlightened our mind with His teaching and laid down a path for His word in our hearing.  Let us give thanks to Him Who has granted His fruit to our tree.
Praise to Him Who invisibly cultivates our spirit. Blessed is He Who attuned the senses of our spirit, that it might ever play songs of exaltation to Him on its lyre.

+St. Ephraim the Syrian, quoted by St. Theophan the Recluse in A Spiritual Psalter: or Reflections on God, psalm 118.

St. Isaac the Syrian: On thankfulness to God

The thanksgiving of the recipient incites the giver to give gifts greater than the first. He that returns no thanks in small matters is a dissembler and dishonest in greater ones also. If a man is ill and recognizes his ailment, his healing will be easy. If he confesses his pain, he draws nigh its cure. The pangs of the unyielding heart will be multiplied, and the patient who resists his physician amplified his torment. There is no unpardonable sin, save the unrepented one. Nor does any gift remain without addition, save that which is received without thanksgiving. The fool's portion is small in his eyes.
+St. Isaac the Syrian, from The Ascetical Homilies, Homily 2 On thankfulness to God, in which there are also essential elementary lessons.