"Unlike in the Solow model, the factors important to the savings decision now enter separately from those important to the investment decision. Aggregate demand pathologies are, nonetheless, impossible, because in Lucas’s model the same agents make both the savings and the investment decision, which insures ex ante coordination, and the agents have rational expectations, which insures that mistakes about the future course of the economy are necessarily unsystematic. Furthermore, the supply of labor responds elastically to temporarily high real wages: workers make hay while the sun shines."
January 1, 1970
https://en.wikiquote.org/wiki/Rational_expectations