Hence, always rid yourself of desires in order to observe its secrets;
But always allow yourself to have desires in order to observe its manfestations.
In a note to these lines, the translator (D.C. Lau) writes: “In translating from the Chinese it is often impossible to avoid using the pronouns ‘it’ and ‘they’ and their derivatives without any clear reference, whether these are expressed in the Chinese or only implied. In the present work ‘it’ used in this way sometimes referes to ‘the way’ and ‘they’ to the ‘myriad creatures’.”
Now, the metaphysical question as to what ‘the way’ (tao) is, is suspended in the very first words of the Tao Te Ching: “The way that can be spoken of/ is not the constant way”. All the usual theological problems apply to ‘the way’. We don’t want to get funnelled into Greek thought; still, the use of ‘it’ for way suggests a unity, as opposed to ‘they’, which indicates plurality.
To discuss these lines, let us accept the ‘it’ does refer to ‘the way’, while also noting that ‘it’ refers to the ‘seat of one’s desires’, the ‘will’, the ‘desirer’. So the text, which is concerned with teaching ‘the way’, starts by telling us to observe desire. Observing our desiring and knowing ‘the way’ belong together.
There’s a lot about (battling) desires in religion, east and west. To start by observing them strikes me as promising, because by observing we both engage and disengage in battle against them.