For Nathan and Will, from Christopher Janaway’s excellent Self and World in Schopenhauer’s Philosophy:

Though they require some supplementation and more detailed argument, Schopenhauer’s central views about action are, I would argue, substantially right. In particular, his claim that the willing that occurs in the case of a successful action is the action itself has great advantages over the volitionalist account. Though mental, willing also becomes a phenomenon in the objective realm; and the relation in which we stand to the movements we make with our bodies is no longer implausibly passive. Whatever doing is precisely, it is essentially something of which the doer is not passively aware, something known to the doer without the mediation of inference or observation; but it is also something that is observable. The actions of which I have that elusive ‘inner’ awareness are events apprehended by others as occurring at some place and time, and indeed by myself as including my body’s moving. There is no room for wholly dualist thinking about self and world once this is accepted, and it is to Schopenhauer’s credit that he shows us this.

Schopenhauer realized too that for there to be an act of will, certain characteristic causal antecedents—what he called motives—had to be present in the mind. It is only when the causal chain ‘passes through the intellect’, when the subject has some objective cognition and entertains some desire with respect to the world, that an act of will can occur. My act of will could have no content if it were not caused by motives, and without content it could not even be an act of will at all. So both an ‘inner’ access to the body’s movements and an appropriate causal history are necessary to account for acts of will—but it is a mistake to look for a distinct mental event called an ‘act of will’ among the causal antecedents of bodily action.

[...]

In the case of free will, Schopenhauer of course leans heavily on Kant. But he demonstrates a more clear-cut awareness than Kant that the deepest problem is not one of uncaused causes, or really much to do with causality at all, but an instance of the same powerful conflict between our aspirations to objectivity and the constraints that being subjects of understanding and will places on how we can regard ourselves. In the case of the pure subject of experience, Schopenhauer works out a much starker form of a conflict that lurks within Kantianism but which Kant did little to address. Though there is a certain crudity in Schopenhauer’s handling of this most delicate of Kantian issues, his very recognition of the larger-scale difficulty is an advance beyond the position that Kant reached. At least in this case and in that of free will, Schopenhauer’s ability was not so much to articulate any very sophisticated response to the issue, as to state it clearly. It is not fanciful to suggest that those interested in problems of ‘the subjective and the objective’, or any of the issues that I have mentioned here, might derive benefit from reading Schopenhauer’s statements of where the problems lie.

This is all quite right, and worth pondering even if it doesn’t solve the mysteries of the Immaculate Conception.