There are no things outside the mind. When the mind generates a thought of filial piety, filial piety is the thing.
"The master of the body is the mind; what the mind generates is intention; the original substance of intention is knowledge; where intention lands is a thing."
爱曰：「如以事亲为例，事亲之际，有温凊定省之许多节目，不知亦须讲求否？」
先生曰：「如何不讲求？只是有个头脑，只是就此心去人欲、存天理上讲求。此心纯乎天理之极，则冬时自然思量父母的寒，便自要去求个温的道理；夏时自然思量父母的热，便自要去求个凊的道理。这都是那诚孝的心发出来的条件。须是有个诚孝的心，然后有这条件发出来。譬之树木，这诚孝的心便是根，许多条件便是枝叶。须先有根，然后有枝叶。不是先寻了枝叶，然后去种根。」
又曰：「心即理也。学者，学此心也；求者，求此心也。」
Xu Ai said: "Using serving parents as an example, during the serving there are many specific protocols like warming, cooling, attending morning and evening. I wonder if these also need to be studied?"
The Master said: "How can they not be studied? But there must be a fundamental focus — one studies only in the context of removing selfish desires and preserving heavenly principle in this mind. When this mind is perfectly pure heavenly principle, then in winter one naturally thinks of one's parents' cold and naturally seeks the principle of keeping them warm; in summer one naturally thinks of one's parents' heat and naturally seeks the principle of cooling them. All these are conditions emanating from that sincere and filial heart. There must first be a sincere and filial heart, and then these conditions emanate. Like a tree — the sincere and filial heart is the root, and the many conditions are branches and leaves. There must first be a root, and then there are branches and leaves. It is not that one first seeks the branches and leaves and then plants the root."
He also said: "The mind is principle. Learning is learning this mind. Seeking is seeking this mind."
In learning any field, first cultivate genuine love and intuition for the field (the sincere filial heart), then learn specific techniques (warming and cooling protocols). Techniques without passion are dead; techniques with passion naturally grow.
"There must first be a sincere and filial heart, then these conditions emanate."
The tree metaphor clarifies the order of effort: root (sincere filial heart) comes first, branches and leaves (specific protocols) come after. With the root, branches naturally grow; without the root, protocols are empty shells. This is why Yangming emphasizes "first establish the great" — first establish the dominance of innate knowledge.
"When this mind is perfectly pure heavenly principle, one naturally thinks of parents' cold."
"Naturally" is the key word. It is not that you first learn "the principle of keeping parents warm in winter" and then mechanically execute it; when the mind is pure heavenly principle, it naturally thinks of parents' comfort. This is the practical meaning of "mind is principle" — when the mind of heavenly principle faces concrete situations, appropriate responses naturally arise.