In connection with the exposition of Compassion here given, as the coming into play of motives directly occasioned by another's calamity, I take the opportunity of condemning the mistake of Cassina,[4] which has been so often repeated. His view is that compassion arises from a sudden hallucination, which makes us put ourselves in the place of the sufferer, and then imagine that we are undergoing =his= pain in =own own person=. This is not in the least the case. The conviction never leaves us for a moment that he is the sufferer, not we; and it is precisely in his person, not in ours, that we feel the distress which afflicts us. We suffer =with= him, and therefore in him; we feel his trouble as =his=, and are not under the delusion that it is ours; indeed, the happier we are, the greater the contrast between our own state and his, the more we are open to the promptings of Compassion. The explanation of the possibility of this extraordinary phaenomenon is, however, not so easy; nor is it to be reached by the path of pure psychology, as Cassina supposed. The key can be furnished by Metaphysics alone; and this I shall attempt to give in the last Part of the present treatise. I now turn to consider the derivation of actions of real moral worth from the source which has been indicated. The general rule by which to test such conduct, and which, consequently, is the leading principle of Ethics, I have already enlarged upon in the foregoing Part, and enunciated as follows: _Neminem laede; immo omnes, quantum potes, juva._ (Do harm to no one; but rather help all people, as far as lies in your power.) As this formula contains two clauses, so the actions corresponding to it fall naturally into two classes. [1] First maxim: it is not in our hearts to identify ourselves with those who are happier than we are, but only with those who are less happy. [2] Stallbaum: p. 584, sq.--(_Translator._) [3] There are no real pleasures, without real needs. [4] _V_. his _Saggio Analitico sulla Compassione_, 1788; German translation by Pockels, 1790. CHAPTER VI. THE VIRTUE OF JUSTICE.