The challenge of metaphors

Many similes link human and plants, so that a creeper around a tree is compared to the arms of a young girl “chained around my neck” (Caurapañcaśikā), and the trees moved by winds in the Rāmāyaṇa rustle and seem “almost …to weep”. Do such literary instances prove something about their authors' view of plants? Did they believe that trees feel love and suffer? By and large, I think that plants in such similes do not express love, etc. It is rather up to poets to read a vegetal behaviour along the line of a human one, so that a creeper is poetically described as wanting to adhere to its beloved tree. Therefore, the burden of the expression of love or grief is on the poet, not on the plants. Similarly, in many Western languages, some sorts of willows are called “weeping willows”, not because one believes them to grieve for something, but rather because their branches, bent downwards, remind us of our behaviour while grieving.

But what about the pre-history of such expressions? Are they grounded in an older belief in the common nature of all parts of the cosmos?