More than appearance

This dog's name is Sandy and she is not like her appearance. When she is around family she is the gentlest animal I have ever seen. She can't seem to get enough affection. However, if you are a stranger, BEWARE! When she shows her teeth she isn't kidding. So, what is her value to the family?

1 Samuel 17:42-45 WEB (R)
(42) When the Philistine looked about, and saw David, he disdained him; for he was but a youth, and ruddy, and withal of a fair face.
(43) The Philistine said to David, Am I a dog, that you come to me with sticks? The Philistine cursed David by his gods.
(44) The Philistine said to David, Come to me, and I will give your flesh to the birds of the sky, and to the animals of the field.
(45) Then said David to the Philistine, You come to me with a sword, and with a spear, and with a javelin: but I come to you in the name of Yahweh of Armies, the God of the armies of Israel, whom you have defied.

To the Philistine, Goliath, dogs weren't worth very much. That is why he talked this way to David. Later, he learned what a mere boy with sticks and stones could do and it cost him his very life. So, I guess the moral of all this is to say that things we value lightly can be of great value if used correctly. Even a dog has value, if there is enough love to motivate it. Believe you me, Sandy is motivated!