Wharton professor and author Jeremy Siegel has stood by his “stocks for the long run” philosophy during the recent bear market. Yesterday on NPR radio, he went even further, saying that he is “virtually sure” that it won’t be a long time before stocks start rewarding investors.

“Looking forward, for everything that I think, it’s certainly going to be much better for investors,” Siegel said. “I’m virtually sure that it’s not going to be a long wait. And the reason is we’re no longer at high points in the market.”

Siegel says he studied the past 100 years of stock market history, and found that once the market is down 50% from its high — as it was in March — “your prospects are very good” going forward.

Another bullish sign, Siegel said, was the fact that the market’s dividend yield is now fairly attractive. In fact, it actually climbed higher than the yield on long-term government bonds back in March — the first time in 50 years that that had happened, he said.

While investors fled to federal paper during the crisis as fear-inducing headlines abounded, Siegel said he thinks that the mass flight to safety has passed. “I actually don’t think there is another shoe to drop or another ‘scare headline’ out there,” he said, “and history has said that is a time to buy.”