'T Derde deel van 't Licht der zee-vaert, inhoudende de beschryvinghe der zeecusten van de Middelandtsche...

...continuing to sail (since one has there increasing or growing westeringh) the Fleur-de-lis will begin to deviate little by little more and more from the north to the west, and the course one sails, just as much from the east to the north. In such a way that when one comes by Cyprus, there the Fleur-de-lis will deviate about a point to the west, and the east a point to the north: so that one (following such a compass) instead of east, will sail east by north, and arriving at the coast of Syria, will have fallen much further north and at a higher latitude than the desired place.

To understand this more clearly through an illustration:
Let A be Malta, where the Fleur-de-lis of the compass points exactly north. B the place on the coast of Syria, at equal latitude: A C D B is then the line of true east and west, and the lines E I F, G K H lines of true south and north. If a ship sails from A to B, at first it sails without noticeable difference along the line A C B exactly east, but the Fleur-de-lis gradually deviating to the west, the east direction of the compass will deviate just as much to the north, and the ship following such a compass, also so much...

...deviating north of the true east, as, having sailed to the length of C, where I assume that the Fleur-de-lis deviates half a point to the west, as from E to Q. and the east half a point to the north, as from L to M; the ship has sailed not along the line A C to C: but through the compass gradually led away from it, along the line A I, to I. Continuing to sail from I to the length of D K G, where I assume that the Fleur-de-lis pulls a point to the west, as from G to P. the east a point to the north, as from N to O: the ship is led by the compass...

A navigational diagram spans the width of the page, illustrating magnetic variation. A horizontal baseline is labeled A, C, D, and B. Three circular compass roses are centered on points A, C, and D. At point A, the 'Lely' (fleur-de-lis) points straight north towards Z. Moving rightwards towards C and D, the Lely progressively tilts towards the west (left) at points Q and P. Dotted lines trace the ship's actual path deviating northwards through points Y, I, and K towards point R, contrasting with the intended straight path along the A-B axis towards X. Various coordinate letters (E, F, G, H, L, M, N, O, S, T, V, W) mark points of alignment and divergence. A decorative compass rose appears in the lower right area of the chart.