Tractatus as manual
Tractatus 6.53 is a comment on the Tractatus-enterprise as such. Earlier, in 4.112, Wittgenstein has stated that the only task for philosophy is ‘the logical clarification of thought’. Strictly speaking this implies that an enterprise such as that of the Tractatus (with its ontology, meaning theory, logic, …) is not philosophy. What it does is define and describe the instruments that the philosopher can use, but that is not the same as actually applying those instruments. So, the Tractatus itself, ie., that definition and description, is ‘strictly speaking’ (which seems to be the right translation of ‘eigentlich’ here) is not what the philosopher can and should be concerned with. In line with that, Wittgenstein indicates in the following (notorious) passage 6.54 how what he has done in writing the Tractatus (against his own better judgment, so to speak) should work: the Tractatus supplies the philosopher’s instruments with an extensive manual, one that not only provides instructions for use but also outlines why the instruments should be used this way. But of course, once we have learned how to use the instruments we can discard the manual. And we should, is what Wittgenstein is saying here: we should not confuse reading and contemplating the manual with the actual employment of the instruments. What holds for the gardener, the construction worker, for any person who is using an instrument, applies to the philosopher as well: the skills that they need come from practice, not from studying the manual.