He who can do not what he wills, should try
      To will what he can do; for since ’tis vain
      To will what can’t be compassed, to abstain
      From idle wishing is philosophy. 
    Lo, all our happiness and grief imply
      Knowledge or not of will’s ability: 
      They therefore can, who will what ought to be. 
      Nor wrest true reason from her seat awry. 
    Nor what a man can, should he always will: 
      Oft seemeth sweet what after is not so;
      And what I wished, when had, hath cost a tear. 
    Then, reader of these lines, if thou wouldst still
      Be helpful to thyself, to others dear,
      Will to can alway what thou ought to do.

[237] See the letter addressed by Lionardo to Lodovico Sforza enumerating his claims as a mechanician, military and civil engineer, architect, &c.  It need scarcely be mentioned that he served Cesare Borgia and the Florentine Republic as an engineer, and that much of his time at Milan was spent in hydraulic works upon the Adda.  It should be added here that Lionardo committed the results of his discoveries to writing; but he published very little, and that by no means the most precious portion of his thoughts.  He founded at Milan an Academy of Arts and Sciences, if this name may be given to a reunion of artists, scholars, and men of the world, to whom it is probable that he communicated his researches in anatomy.  The Treatise on Painting, which bears his name, is a compilation from notes and MSS. first printed in 1651.

[238] The folio volume of sketches in the Ambrosian Library at Milan contains designs for all these works.  The collection in the Royal Library at Windsor is no less rich.  Among Lionardo’s scientific drawings in the latter place may be mentioned a series of maps illustrating the river system of Central Italy, with plans for improved drainage.

[239] Shelley says of the poet:—­

    He will watch from dawn to gloom
    The lake-reflected sun illume
    The yellow bees in the ivy bloom;
    Nor heed nor see what things they be,
    But from these create he can
    Forms more real than living man,
    Nurslings of immortality.

[240] See De Stendhal, Histoire de la Peinture en Italie, p. 143, for this story.

[241] In the Treatise on Painting, da Vinci argues strongly against isolating man.  He regarded the human being as in truth a microcosm to be only understood in relation to the world around him, expressing, as a painter, the same thought as Pico. (See Vol.  II., Revival of Learning, p. 35.) Therefore he urges the claims of landscape on the attention of artists.

[242] I might refer in detail to four studies of bramble branches, leaves, and flowers and fruit, in the royal collection at Windsor, most wonderful for patient accuracy and delicate execution:  also to drawings of oak leaves, wild guelder-rose, broom, columbine, asphodel, bull-rush, and wood-spurge in the same collection.  These careful studies are as valuable for the botanist as for the artist.  To render the specific character of each plant with greater precision would be impossible.