Three times in the Old Testament (2 Kings 18:21; Isaiah 36:5-6; Ezekiel 29:6-7), God compared Egypt to “a splintered reed.” Reeds are long, thick grasses that grow along the banks of rivers such as the Nile. Egypt is a dry land, and agriculture is possible only because of irrigation from the Nile River. As a result, Egypt has very few trees. The Egyptians made boats out of carefully constructed bundles of reeds. (They also made rope, baskets, and paper out of a similar aquatic plant, papyrus.)
This image shows God’s sense of humour. Imagine trying to use a reed as a staff, walking stick, or cane. As soon as you leaned on it, it would splinter. The Jews were depending on Egypt to defend them against invasions by the Assyrians and Babylonians. God said that depending on the Egyptian army for defence was as silly as trying to use a reed as a walking stick. Egypt had once been a powerful empire, but it was that no longer. But the real problem was that the Jews were relying on Egypt instead of their God, who was much more powerful and will always remain so.
I suspect that this image has other applications. The things that many modern people rely on are as weak and undependable as a reed walking stick. We make use of many things in the modern world, including wood and steel, hard work, reason, science, and modern medicine. There is nothing wrong with using any of these tools. God created them for our use. The danger is in relying on them without first relying on God. God can use any of these things to help us. God can also overpower any and all of these things when we do not first rely on God. Psalm 127:1 reminds us that “Unless the Lord builds the house, the builders labor in vain. Unless the Lord watches over the city, the guards stand watch in vain.” This does not mean that we should not build or take precautions. We should. It does mean that we should recognize the sovereignty of God over all of these things.