She sent her _Defence_ to Leibnitz, who criticised it at considerable
length:--[3]

"J'ai lu livre de Mlle. Trotter. Dans la dedicace elle exhorte M.
Locke à donner des démonstrations de morale. Je crois qu'il aurait
eu de la peine à y reussir. L'art de démontrer n'est pas son fait.
Je tiens que nous nous appercevons sans raisonnement de ce qui est
juste et injuste, comme nous nous appercevons sans raison de
quelques theoremes de Geometrie; mais il est tousjours bon de venir
à la démonstration. Justice et injustice ne dependent seulement de
la nature humaine, mais de la nature de la substance intelligente
en général; et Mlle. Trotter remarque fort bien qu'elle vient de la
nature de Dieu et n'est point arbitraire. La nature de Dieu est
tousjours fondée en raison."

Notwithstanding all this, the commentators of Locke appear, without
exception, to ignore the _Defence_, and it was probably never much read
outside the cultivated Salisbury circle.

In this year, 1702, the health of Catharine Trotter began to give her
uneasiness, and it was for this reason that she left Salisbury for a
while. She was once more living in that city, however, from May 1703 to
March 1704, making a special study of geography. "My strength," she
writes to George Burnet, "is very much impaired, and God knows whether I
shall ever retrieve it." Her thoughts turned again to the stage, and in
the early months of 1703 she composed her fifth and last play, the
tragedy of _The Revolution in Sweden_; "but it will not be ready for
the stage," she says, "till next winter." Her interest in philosophy
did not flag. She was gratified by some communications, through Burnet,
with Leibnitz, and she would have liked to be the intermediary between