Fed Vice Chairman Stanley Fischer offered his most-revealing comments yet in a speech in Stockholm today. The former Bank of Israel governor planted himself on the dovish side of the Fed ledger by focusing on the low participation rate and soft housing market.

He said slower growth may signal a structural shift but it’s an “open question”. On participation he said aging is the main reason (although at 70, he’s another example of older Americans working longer) but said there is “considerable uncertainty” about how much is because of cyclical conditions.

“Many of those who dropped out of the labor force may be discouraged workers. Further strengthening of the economy will likely pull some of these workers back into the labor market,” he said.

Overall, Fischer was reluctant to say anything bold or clear but the tone of his speech showed someone in no rush to raise rates. One school of thought says the Fed should hike to minimize financial risks in the economy but he expressed some confidence that the Fed has other tools.

Fischer could have been an ally to the dollar bulls but his cautious tone instead gives the slow-moving Yellen someone to support her patient approach toward raising rates.