David spoke these encouraging words to the king about Goliath: “Let no one lose heart because of him.” Saul and his men had indeed lost heart because of Goliath. Perhaps they had made the natural mistake of comparing themselves to that huge man, picturing how they came up only to the man’s midriff or chest. They imagined that armored giant making short work of them. But David did not think that way. As we will see, he saw the problem in a completely different light. So he offered to fight Goliath himself.​—1 Samuel 17:32.

David was not blind to Goliath’s size or his weapons. Yet David refused to let such things daunt him. He did not make the mistake that Saul and the members of his army did. David did not compare himself to Goliath. Instead, he looked at Goliath in comparison with Jehovah. Standing some nine and a half feet (2.9 m) tall, Goliath towered over other men, but how big was he compared to the Sovereign of the universe? Really, like any human, he was barely more than an insect​—in this case, one that Jehovah was ready to exterminate!

David ran toward his foe, reaching into his bag for a stone. He loaded his sling and whirled it over his head until it fairly whistled. Goliath, perhaps close behind his shield-bearer, advanced toward David. Goliath’s great height may actually have been a disadvantage for him, since a shield-bearer of normal size could hardly have raised a shield high enough to protect the giant’s head. And that is just where David aimed.​—1 Samuel 17:41.

The Bible says that Goliath’s “height was six cubits and a span.” (1 Samuel 17:4) The cubit in question was 17.5 inches (44.5 cm) long; the span, 8.75 inches (22.2 cm). That adds up to about nine feet six inches (2.9 m). Some insist that Goliath could not have been that tall, but consider: In modern times, the tallest man documented was over 8 feet 11 inches (2.7 m) tall. Is it really impossible that Goliath was six inches (15 cm) or so taller? He was of the tribe of the Rephaim, men who were known for their unusual size. An Egyptian document from the 13th century B.C.E. mentions that some fearsome warriors in the region of Canaan were over eight feet (2.4 m) in height. So Goliath’s height, while unusual, is hardly impossible.