The three distinct treatises of which the _Praeludia Botanica_ consists were written probably at different times, though published simultaneously in 1669. The first of them is an alphabetical catalogue, comprising about 2600 species, of the plants in the Royal garden at Blois when under Morison's care: 260 of the species are marked as new, and are fully described in an appendix. But the chief interest of the _Hortus Regius Blesensis Auctus_ lies in the dedication to King Charles II. Morison here narrates how, whilst at Blois, he had framed a system of classification; how the King's Uncle, the Duke of Orleans, had promised to undertake the publication of a book to illustrate the system on an adequate scale, and how the sudden death of the Duke in 1660 had destroyed all such hopes; and he ends by appealing to the King to give him the patronage that he so much needed. "_Quod si annuere hoc mihi digneris_," he wrote, "_polliceor Britanniam vestram cum methodo exactissima (quae est naturae ipsius) imposterum, in re Botanica gloriari posse, quemadmodum Italia, Gallia, Germania, superiori saeculo, sine methodo, in Scientia Botanica gloriatae sunt._" But the King does not appear to have been moved by this dazzling promise. Morison evidently did not suffer from any lack of confidence in himself or in his method, of which he speaks on a previous page of the dedication, as "_methodus nova a natura data, a me solummodo (citra jactantiam) observata: a nullo nisi meipso in hunc usque diem detecta, quamvis mundi incunabilis sit coeva_," language which can hardly be described as modest. And yet, curiously enough, Morison gives not the slightest indication of the principles of this altogether new and original method of classification. The second treatise, the _Hallucinationes_, is a searching and acute criticism of the published works of the brothers Bauhin: of the _Pinax_ of Caspar, and of the _Historia_ of John. Though he acknowledges in the preface the great value of their botanical labours, Morison did not fail to set out in detail the mistakes that they had made in both classification and nomenclature, and to make corrections which were, for the most part, justified. Probably it was the critical study of the works of the Bauhins that led Morison to frame a system of classification of his own.