The Psalm declares: "Ma niml'tzu l'chiki imratecha mi'dvash l'fi" - 'How sweet to my palate is Your word, more than honey to my mouth.'
In Ruth (3:7) 'Boaz ate and drank and his heart was merry.' Sweets accustom the tongue to words of Torah..
Midrash Tanchuma (Chukas 1): 'Saliva is sweet (while tears are salty) - because man recites Torah in his mouth, and words of Torah are sweeter than honey.'.
Talmud Yerushalmi (Taanis 4:5): 40 years prior to the Babylonian exile, G-d caused that date trees were planted there. Date honey is sweet and eating sweets accustoms the tongue to search out the sweetness of Torah (also Pesachim 87b).
A Jewish custom is to drop honey on the letters when a small child is learning aleph bais, and allowing the child to lick the honey from the letters, so that the child will always associate the letters of Torah with sweetness.

- From Artscroll - Tehillim p. 1466