For a New Liberty

While rereading For a New Liberty (first published in 1973) recently, I confess I was puzzled ... Here's the passage that had me scratching my head:

Let us waive, for the moment, the question of original property rights in the clay and the sculptor's tools. The question then becomes: Who owns the work of art as it emerges from the sculptor's fashioning? ... He has placed the stamp of his person upon the raw material, by "mixing his labor" with the clay, in the phrase of ... John Locke. And the product transformed by his own energy has become the material embodiment of the sculptor's ideas and vision.

Political philosophy ... can't identify the aggressor and victim in particular cases; relevant empirical information is required. Murray Rothbard wrote in For A New Liberty:

If, for example, we see X seizing a watch in the possession of Y we cannot automatically assume that X is aggressing against Y's right of property in the watch; for may not X have been the original, "true" owner of the watch who can therefore be said to be repossessing his own legitimate property? In order to decide, we need a theory of justice in property, a theory that will tell us whether X or Y or indeed someone else is the legitimate owner.

In 1973 ... Murray Rothbard issued a comprehensive popular presentation of the libertarian philosophy in For a New Liberty: The Libertarian Manifesto, first published by the mainstream publisher Macmillan. The book is an excellent discussion of libertarian principles and applications ... "Emotivists," he wrote, "assert that they take liberty or nonaggression as their premise purely on subjective, emotional grounds." He was undoubtedly dissatisfied with that "foundation" ... Anyone eager to understand the rich libertarian philosophy and heritage could do no better than to begin with For a New Liberty.