New Defender's Study Bible Notes
8:5 he goat. This “he-goat” represents the Greek empire (Daniel 8:21), which Daniel prophesied would eventually conquer the Medo-Persian empire, just as he had prophesied the latter would conquer the Babylonian empire. These events, of course, came to pass as predicted. The fact that the ram is Medo-Persia and the goat is Greece provides further indication that the bear and leopard in Daniel 7 were not these two kingdoms, as many take them to be, but rather two great kingdoms of the end-times.
8:5 notable horn. This “notable horn” on the goat is said to be the “first king” of the future conquering Greek empire (Daniel 8:21)—none other than the famous Alexander the Great, whose conquests were so swift that it seemed like his legions “touched not the ground” as they advanced.