The phrase "a source of desire" is correct and usable in written English.
It can be used to describe something that evokes or generates feelings of longing or want.
Example: "The beautiful landscape served as a source of desire for many artists seeking inspiration for their work."
Alternatives: "a wellspring of longing" or "a catalyst for yearning".
In this context Lessing presents a pantheism that characterizes the one and only substance, not only as a source of motion and desire, but also as capable of representing every possibility to itself and approving that possibility that constitutes "the best and most perfect series of things" (Morning Hours, p. 84/Gesammelte Schriften 3/2, p. 115).
Find a source of plastic that you desire to recycle into a useful object.
In analyzing the creation of the Polish Legions, many historians have argued that Napoleon used the Poles as a source of recruits and had little desire to invest in the re-creation of the Polish state.
This can of course be a source of conflict due to differing levels of desire.
Whatever its own defects may be, the order that science discloses in nature is, by its indifference to our desires, a source of discipline.
Goals provide a source of motivation, representing targets or desired outcomes of self-regulatory activity, concepts which structure and direct behaviour (Carver and Scheier 1998).
The Eastern worldview recognizes the source of desire as the cause of all suffering.
Desire "is a source of suffering, pain and hatred".
What's also interesting is that Facebook is clearly outlining how its goal to be a utility supersedes its desire to be a source of entertainment, though both are important.
In a letter written around the same time as Three Guineas, Woolf not only acknowledges that gender-specific traits are socialized, but implies that gendered desires are often a source of violence.
