A rare coin is worth exactly what it can be sold for, or what is currently being bid for it—no more, no less. Once a definite price trend is established, it tends to continue; the longer the trend has existed, the more reliable it is. Prices tend to move in the direction of the least resistance; past market history indicates what this direction has been. The best and safest investments in rare coins are those that have proven their monetary value by repeated tests in the market over a long period of time. Alexander the Great conquered the ancient province of Bactria (present-day Afghanistan) during his march to India. Although Greek art was generally in decline by the time of Alexander, the coinage of the short-lived Graeco-Bactrian kingdom was outstanding, as this portrait coin of a warrior attests. Alexander introduced both Greek art and Macedonian gold coinage to the Middle East, and while his military con- quests proved ephemeral, these cultural achievements left a permanent mark.