Taṇhā: Craving
Craving is the thirst that always reaches for more. The thorns crowding the seedling are this thirst, already rooted in the soil before the word ever lands, drinking the same water and blocking the same sun. A heart packed with wanting keeps no open ground for a slow shoot, so the deepest root wins, and it is seldom the word. The soil held plenty already, just the wrong crop.
Lokadhamma: The eight worldly winds
The eight worldly winds blow a person between gain and loss, praise and blame, comfort and pain. The cares of this age are these same winds: chasing the gain, dreading the loss, so busy bracing against each gust that the young shoot underfoot gets trampled. Ground worked only to catch the next favorable wind grows thorns well and wheat poorly.
Moha: Delusion
Delusion is the fog that keeps us from seeing how things stand. The deceitfulness of riches lives in this fog: the gold itself stays silent while the mind whispers that enough of it buys safety, that a full barn means a settled heart. Believing the whisper, a person guards the barn all day and never tends the seed, then wonders why nothing grew.
Nīvaraṇa: The five hindrances
The five hindrances smother a clear mind, sense-hunger and restless worry among them. To choke the word is their plain work: desire and anxiety wind around the shoot the way bindweed winds around a stem, tightening a little more each anxious day until the sap cannot rise. It dies by slow steady squeeze, from a mind too crowded to breathe.
Bhāvanā: Cultivation
Cultivation is the daily tending of the mind. Becoming unfruitful is what befalls good ground left alone: the seed was sound and the rain came, yet no hand ever pulled a weed, so the thorns simply outlasted the wheat. The word does not fail for any lack of truth in it; it fails for the lack of anyone clearing a little room around it each morning.