Final causality too must be regarded as immanent to nature, and precisely because efficient causal powers are. For Aquinas, there is no way to make sense of the fact that an efficient cause A regularly generates a certain specific effect or range of effects B -- rather than C, or D, or no effect at all -- if we don’t suppose that A inherently “points to” or is “directed at” B as toward an end or goal.
Immanent efficient causal power goes hand in hand with immanent finality or directedness; deny the latter and you implicitly deny the former, which is why Humean skepticism about efficient causality as a real, objective feature of the world followed upon the early moderns’ chucking-out of immanent final causes. (source: "
Metaphysical Middle Man" by Edward Feser, Thursday, January 31, 2013)