illustration (attribution, if any possible, is at the end of the article)
Buddha-nature is regularly misunderstood, and it then may be interpreted e.g. as "we're already enlightened". This is not what the doctrine of buddha-nature actually says!
This misunderstanding might lead to complacency: if I'm already enlightened, or if the seeds of enlightenment are already in me and will automatically mature in due time, I don't need to do any spiritual 'work'… Buddha-nature would then seem rejecting "right effort", one of the pillars of the eightfold path, one of the fundamental admonitions of any school, etc.
Daito Kokushi's (Zen) admonition to new monks was: « O you, monks, who are in this mountain monastery… Remember that you are gather here for the sake of religion and not for the sake of clothes and food. As long as you have shoulders [that is, a body], you will have clothes to wear, and as long as you have a mouth, you will have food to eat.
Be ever mindful, throughout the twelve hours of the day, to apply yourselves to the study of the Unthinkable. Time passes like an arrow, never let your minds be disturbed with worldly cares. Ever, ever be on the look-out. (…) »
"Buddha-nature" is related to "emptiness of essence" (śūnyatā) doctrine.
It states that the difference between you and buddhahood is empty of essence, i.e. nothing intrinsically, inherently, fundamentally prevents you from becoming a buddha.
This does not say you're a buddha already, or that you'll automatically become one.
As a consequence, the doctrine promotes effort: because nothing intrinsically prevents you from becoming a buddha, effort is valuable, effort makes a real difference up to buddhahood!
If there were an intrinsic barrier, effort would only lead you up to the barrier. But there isn't, hence effort is valuable and can lead to nirvāṇa!
Apply yourself! Which is to say: "Don't know! Pay attention!"
• "The five aggregates and buddha-nature":
• "Training, trusting your buddha-nature":
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Photo: Gandhara Buddha (1st–2nd century CE). Tokyo National Museum.