If I had reflected when I began to speak in this manner that I should have to act up to my words, I should certainly have said much less; but as it was, the duke fancied that I knew much more than I cared to say.  The result was that, when the company had risen from the table, he asked me if I could spare him a fortnight on my way to St. Petersburg.  I said I should be glad to oblige him, and he took me to his closet and said that the chamberlain who had spoken to me would conduct me over all the mines and manufactories in his duchies, and that he would be much obliged if I would write down any observations that struck me.  I agreed to his proposal, and said I would start the next day.

The duke was delighted with my compliance, and gave the chamberlain the necessary orders, and it was agreed that he should call for me at day-break with a carriage and six.

When I got home I made my preparations, and told Lambert to be ready to accompany me with his case of instruments.  I then informed him of the object of the journey, and he promised to assist me to the best of his ability, though he knew nothing about mines, and still less of the science of administration.

We started at day-break, with a servant on the box, and two others preceding us on horseback, armed to the teeth.  We changed horses every two or three hours, and the chamberlain having brought plenty of wine we refreshed ourselves now and again.

The tour lasted a fortnight, and we stopped at five iron and copper manufactories.  I found it was not necessary to have much technical knowledge to make notes on what I saw; all I required was a little sound argument, especially in the matter of economy, which was the duke’s main object.  In one place I advised reforms, and in another I counselled the employment of more hands as likely to benefit the revenue.  In one mine where thirty convicts were employed I ordered the construction of a short canal, by which three wheels could be turned and twenty men saved.  Under my direction Lambert drew the plans, and made the measurements with perfect accuracy.  By means of other canals I proposed to drain whole valleys, with a view to obtain the sulphur with which the soil was permeated.

I returned to Mitau quite delighted at having made myself useful, and at having discovered in myself a talent which I had never suspected.  I spent the following day in making a fair copy of my report and in having the plans done on a larger scale.  The day after I took the whole to the duke, who seemed well pleased; and as I was taking leave of him at the same time he said he would have me drive to Riga in one of his carriages, and he gave me a letter for his son, Prince Charles, who was in garrison there.

The worthy old man told me to say plainly whether I should prefer a jewel or a sum of money of equivalent value.

“From a philosopher like your highness,” I replied, “I am not afraid to take money, for it may be more useful to me than jewels.”