In the 17th century Europeans started building a world. They felt a need to explain things. This world they started building was a world inside their heads, a world of explanation. Why was this necessary? Because as for the "real" world or the world of experience—that one they had. It was at this time, when there had come to be great cities, and some of the physical structures that correspond to and complement civilization, that they felt the need to bring some explanations into it. They began to build up the explanations that served as the corollary of this civilization that was developing, or sprouting, all around.
The world around them had grown up. The world had changed. Now they needed to come up with the explanations for it. Where did all these buildings come from? Suddenly, the constructions needed to receive the accompanying explanations, that is to say: the "explain" component.
In other words no sooner did a built-up, civilized world begin to "be," than there began to appear (only slightly later) the intellectuals, bent upon this task of explanation—the project of explaining, or of creating a narrative story. They needed the explanation to go with this organized and increasingly sophisticated environment. Thus, 17th century Europe has its complement of scientists and intellectuals. All of them labored to build a world. This time, a world of explanation: they needed one of those.
The world had grown. Now we had a bigger world: one that required a bigger explanation. Where did all the fancy buildings come from? And: why was wealth (and science and technology) increasing (for a few)? The textiles were getting finer. The world itself was getting finer, more refined and extensive. How could that happen without the act of explanation? What these philosophers, scientists and intellectuals were doing was engaging in the mind's need to know, the act of explaining. Life could scarcely go on—how could it?— without the act of creating a narrative, the narrative that was needed to accompany their world's mysterious enlargement? Let's get rid of all those fancy verbs, though, and just call it "the explain."
And thus, Oliver Sacks, in his book (1995), refers to the "sensationalist" theory that Locke upheld, in parallel with some work that Isaac Newton was doing, at the same time. They provided the explanatory nattative society needed. Any view would have worked. Sacks sums up the situation well in an excellent paragraph, p. 20. Sacks understands "sensationalist" theory as a "doctrine," and the ensuing objections to any contradictory evidence, i.e. contrary to the Lockian/Newtonian view, as "doctrinal in nature." Yet, this is the life work of these people --- of the 17th century scientists/philosophers. Nevertheless, it seems that, for us educated persons of today, it can be summarized in the writer's one brief paragraph. (Sacks 1995)
The theory of Locke comes across as quaint. But it was not quaint to the 17th cent. philosophers. No --- because it was the only "explain" they had available.
If the only show in town is a dancing elephant you are going to be enchanted by that elephant. Any view would have worked equally well. They did not see it as quaint; because, they did not have any other explanation.