Because of the occasional necessity and their ability for people to perform different duties, it is important to learn to distinguish the nature of a person from the present expression of it so that discovery may be made of the limits of their abilities: a person can never express a greater nature than they have attained, unless they grow stronger to grow their nature. Similarly, within that expression of nature exists a diversity of skill: just because a woman is a warrior does not mean she has mastered every weapon; just because a man might be a businessman does not mean that he may successfully undertake wholesale, retail, manufacturing, trade, finance, or the very numerous other skills of his nature. Indeed, though that warrior may live by business, she remains capable of wielding weapons - but that businessman cannot wield a weapon, until he grows his nature, grows strong enough in body, mind and heart to wield weapons - and learns the new skills of those weapons.
It is possible to discern of which caste a person is naturally, and to discover their skillful abilities, their strengths and potentials. But it is also possible to discern whether a person is a friend or an enemy, or neither a friend nor an enemy, or partially a friend and partially an enemy.
There are several ways that nature is discovered: a person may become stressed, and thus develop requirement for particular skills or to exhibit particular nature. For example, by requiring a person to fight, you will quickly discover the means by which they engage an enemy: whether by diplomacy, weapons, economics, or sabotage. The defense used by those who, by necessity, must present a different nature than their true nature against being discovered is to recognize the attempt at discovery, and bring an end to the requirements developed through stress, either by fleeing or by engaging the stressor. Stress is caused by fear or hope, and thus inspires action.
Another way nature can be discovered is by intoxication: the subject may become tricked by the numerous skills of Maya to reveal their nature without the necessity of stressing them. The only defense against this is skill in Maya, that the illusionary result of the intoxicant may be understood. Then, the subject may either evade the attempt, or in turn deceive the deceiver. Intoxicants take many forms, and are not limited to alcohol or drugs, but are any substance which relies on pleasure or pain to alter the senses.
Another way nature can be discovered is by long-association, or thorough investigation of their past, their associates and present circumstances. Discovery by this means is unavoidable, for the evidence of a person's past can be only confused, but never utterly obscured.
The identity of a person is best discovered, however, by analysis of the person's actions: they are compelled to perform the duty of their caste, and will always do so, regardless of the form they present. Analyze the intended and unintended results of a person's effort, as well as their conscious and unconscious efforts, if you would know their nature. Observe what they sacrifice, how, and to whom, if you would know their Teacher. Observe their opposition if you would discover their war.
How to examine a teacher – Anguttara Nikaya 10.24
When Maha Cunda was staying among the Cetis at Sahajati, he addressed the monks there, saying,
Whenever a monk brags and says, “I know the Dharma, I see the Dharma, I am developed in body, developed in mind, developed in heart,” by simply bragging, it is clear that he is not. It is clear he does not know he is suffering, how his suffering came into being, how his suffering may end, or the path leading to the ending of his suffering. If he had awareness of his suffering, how his suffering came to be, how his suffering may end, or the path leading to the ending of his suffering, if he had ended his suffering, he would not be compelled to brag, for it would be evident without his flaunting it, and he could simply answer, and demonstrate if necessity required.
When a man becomes wealthy and propertied, it is not necessary that he flaunt his wealth or brag about it. Everyone can see that men come to him for advice on matters of business, or to ask for investment, or in times when money is required. They do not go to a poor man, no matter how much he claims to be wealthy, for when required, the poor man can provide no money for investment or loan, and his advice is bad. It is only a poor man who goes around bragging that he is wealthy and flaunting his wealth.