Böhm-Bawerk’s greatest contribution was his explanation of why exists. Before him, many economists struggled to explain why a dollar today is worth more than a dollar a year from now. He proposed three "reasons" (or grounds) for this phenomenon:

Here is his masterstroke. Present goods can be used in roundabout production processes to create even more goods in the future. Because a farmer with seeds today can grow a crop by next year, the seeds today are technically worth more than a promise of seeds next year.