The manner in which the idea of the _Sylva_ originated is clearly shewn by what is noted in his Diary on 15th October, 1662.--‘I this day deliver’d my “Discourse concerning Forest Trees” to the Society, upon occasion of certain queries sent to us by the Commissioners of his Majesties Navy, being the first booke that was printed by order of the Society, and by their printer, since it was a Corporation.’ This latter reference evidently anticipates events, as one often had reason to note in this so-called diary, because Sylva was not actually published until the beginning of 1664, when along with it were included _Pomona_, and the _Kalendarium Hortense_. In February, 1664, ‘16th, I presented my “Sylva” to the Society; and next day to his Majestie, to whom it was dedicated; also to the Lord Treasurer and the Lord Chancellor.’ There is no doubt that _Sylva_ was a work of national importance. Then, as now, England was dependent on her Navy. But the stock of Oak timber suitable for the requirements of the naval dockyards had become almost exhausted. From a tonnage of 17,110 tons in 1603, our fleet had risen to 57,463 tons in 1660, and during the 25 years of Charles II’s reign it increased to 103,556 tons. To supply these rapidly expanding requirements the stock of timber in the country was feared to be inadequate. From 197,405, loads of timber fit for the Navy in the New Forest in 1608, the stock sank later to 19,873 in 1707; and in the royal forests in Gloucestershire a similar state of affairs obtained. At a meeting of the Council of the Royal Society in November 1662, Evelyn followed up his recent _Sylva_ by suggesting a discourse ‘concerning planting his Majesty’s Forest of Deane with oake, now so much exhausted, of ye choicest ship-timber in the world.’ This was before the days of steam or even of macadamized roads, when we had to grow our own supplies of food and Navy timber. True, oak for wainscoting and the like had long been imported from the Continent; but if we had been anything like dependent on foreign oak, the Dutch War which shortly afterwards broke out would probably have cut off the same entirely from reaching our ports.