Citta: Heart-mind
Citta is the heart-mind, the field where every seed of teaching comes to rest. Whether it is packed hard by habit or turned open and ready decides what a single word can do once it arrives, since the same grain takes root in one heart and dies on the next. The soil matters more than the sower, so a prepared heart grows a small word while a hard one lets the finest teaching roll straight off.
Ayoniso manasikāra: Unwise attention
Ayoniso manasikāra is shallow attention that never reaches the root of a thing. The roadside is packed hard by constant traffic, so the seed sits on top and cannot sink in, and a mind crossed all day by hurry and noise takes in the word the same shallow way. Hearing still happens, yet nothing is turned over or worked in, so the teaching lies exposed on the path where anything passing can carry it off.
Avijjā: Ignorance
Avijjā is the root not-knowing, the dark in which nothing is seen for what it is. A word can cross the ear and still fall into this dark, understood by no one, so it carries no weight and is set down again without notice. A coin dropped in an unlit room is easy to lose, and a teaching that was never understood is the easiest thing of all to lose.
Māra: The tempter
Māra is the pull toward forgetting and sleep that keeps beings from waking. He is the evil one waiting at the roadside, moving the instant a seed lies unguarded and carrying it off before it can send down a root. Receive a good word carelessly and this snatching is already on its way, quick as birds dropping onto scattered grain, for anything not taken in deeply stays his to take.
Bhāvanā: Cultivation
Bhāvanā is cultivation, the slow growing that turns a heard word into a changed life. The roadside seed never reaches it, because with no soil to sink into and no time before the birds it stays a bare grain and comes to nothing. Understanding is the plow that breaks the ground open, and where the ground is never broken there is no root, no fruit, and no harvest to bring in.