Vasana are the seeds of desires and inclinations, the vibrations in our being even before thought.
They are the automatic tendencies that condition our behaviour and personality. They generate the habits that become stronger with repetition, and that weaken when disciplined.
Repeated action/thought generates grooves in the mind stream. As we think and do, we are and become.
Vasana does not signify a ''bad'' thing....it just means the latent forces that form our personality, both shadow and light. They continually weave the cloth of our mind substance keeping our idea of ourselves alive.
Vasanas are habits of the mind. They are the mistaken identifications and the repeated thought patterns that occur again and again. It is the vasanas which cover up the experience of the Self. Vasanas arise, catch your attention, and pull you outwards towards the world rather than inwards towards the Self. This happens so often and so continuously that the mind never gets a chance to rest or to understand its real nature.
Cocks like to claw the ground. It is a perpetual habit with them. Even if they are standing on bare rock they still try to scratch the ground.
Vasanas function in much the same way. They are habits and patterns of thought that appear again and again even if they are not wanted.
~ Annamalai Swami
Before any thought arises, before any action is visible, there is a vasana arising within us, like a breeze that pushes or a seed that insists it must sprout.
Vasanas are quite enduring, just as a stone has been sculpted by erosion the patterns and tendencies of our personalities have been strongly shaped by our experiences and unconscious reactions to them.
Even enlightened humans still have vasana. They still act out of ingrained habits, are grumpy, lazy, eccentric, humorous and so on according to well established grooves.
''Owing to the fluctuation of the vasanas, realization takes time to steady itself.'' ~ Ramana Maharshi
Vasanas are rooted in such deep childhood (or previous lifetimes) conditioning and shocks that they are difficult to eradicate. But not impossible.
Cognitive awareness can help loosen vasana. Simply to practise noticing habitual action, thought and reaction, and staying relaxed, not responding, just aware. Letting it crop up, and in time it will burn off.
Doesn't mean they will dissolve straight away. That river has been running along that bed for a long time. Ding, dong, the bell rings the same note it always did, again and again, until one day....maybe... it falls silent. In the meantime we do not have to jump up like automatons and dance a jig to the call of every bell.
Weeds will always be there in the garden. They are not bad, per se, they just are....We can live with weeds, even love them, but weeds can easily take over. Cultivation of the right plants and uprooting of the ones we do not wish to flourish is what creates the garden that suits us.
Sorry for all the metaphors :) It's my vasanas what done it.