Sister Mairi Jean
Der Naturen Bloeme, 1350 , by Jacob van Maerlant
Der Naturen Bloeme was a translation of De Natura Rerum (approximately 1240 ) by Thomas of Cantimpre , consisting of several hundred poetic entries on all known plants, animals and types of human thought to exist at the time. “In thirteen books he successively dealt with man, quadrupeds, birds, sea monsters and fishes, reptiles and insects, trees, spices and medicinal herbs, springs, precious stones and the seven metals” . Eleven of the thirteen books still survive, seven of them illuminated .
It must be noted that there is some argument as to the date of the creation of Der Naturen Bloeme, with Literatuur Geschiedenis  dating the work to as early as 1270. In addition,  dates van Maerlant’s death to 1300.
Many “iiij. voeten beeste”  (four footed beasts, or quadrupeds) were depicted and described in verse by van Maerlant, including but not restricted to apes, baboons, bears, centaurs, unicorns, gazelles, giraffes, rabbits, cats, lions, leopards, mice, rhinoceros, otters, “pegasus”, reindeers, tigers and wolves.
Two illuminated pictures of lions were included in the original, one of which is reproduced here. The text accompanying the picture is appended and translated after the References.
The size of the illuminated piece is the exact size of the original . I have used guache paint, which is authentic, according to .
“The Dutch miniaturists did not always use gouache; other techniques were considered equally good for the illustration of their manuscripts. In some Bibles, pen drawings appear side by side with gouache miniatures. These drawings must not be considered primary sketches that were supposed to receive the gouache afterward; they are too finished, too complete in themselves; a layer of paint would have destroyed the refined quality of drawing. Furthermore, there are manuscripts entirely illustrated by pen which cannot be unfinished books” (p. 26). 
I used good quality card, whereas the original was on vellum.
Approximately half the text on lions, from Der Naturen Bloeme
Original Old Dutch 
Leo, segt Solinus jeeste,
es coninc van iiij. voeten beeste.
Leewe es hi in Dietsch ghenant
ende liebard heetemen hier int lant.
Men vindet, horic visiren,
van liebarden iii. manieren:
curte vintmen als ende als
ru ghehard, kersp inden hals;
mar die ne sijn no starc no snel.
Andre vintmen also wel
dat perdus winnete, dat wreede dier;
die ne sijn no wreet no fier,
noch oec inden hals oec gemaent.
Mar edele lione, als men waent,
sijn lanc ende smal, ende slecht ghehard,
snel ende starc, ende onvervard.
Sine weten ghene scalchede
no negheen bedrieghen mede;
simpel es die sien van desen
ende also wilsi besien wesen;
hare vorhoft ende start doet
verstaen hoe hi es ghemoet.
In barste ende in voete voren
ligghen hare crachte, als wijt horen.
So heet sijn si, alsi riden
hare ghenoete willen tallen tiden.
Die liewinne brinct eerst .v. jonghe,
dan iiij. ten andren spronghe,
dan iii. dan .ii. dan .i.
dar na nemmermee negheen.
Twe spenen hevet, ende die clene,
middel an haren buuc allene.
Augustinus die seget
alse die lewinne hare jonc leget
dat si in .iii. daghen ne waken.
Dan comt die vader claghe maken
ende grongieren ende mesbaren,
dan onwaecsoe te waren.
Ende dese slaep ghelijct der doet;
dits van beesten wonder groet
Solinus seit in sijn gedichte:
men quetsene, hine belcht niet lichte;
mar maecmenne erre so es verloren.
Al dat hem qomt te voren
nochtan sparti, dats heren doen.
Twi draghen si in den scilt .i. lioen,
ende sine int herte niet draghen?
Vindsi were, si laten em jaghen,
mar den armen ende den verwonnen
dies dien sparen niet connen.
Vint dat lion oec, sonder waen,
enen man die was ghevaen,
dien ne comti altoes niet an.
No verbitet oec den man,
het ne dadem hongher alte groet.
Houder oec hi den man doot
dan twijf, dats grote edelhede;
ende houder doeti vrouwen mede
dan magheden onbesmet.
English (my own translation, heavily influenced by Babel Fish , and less heavily by the Medieval Bestiary )
Leo, the lion (those here in Flanders are called “liebaard”) are the king of the quadrupeds, we read in the writings of Solinus. There are three types of lions. Lions of the first type are small and have harsh fur and a curling mane. These lions are not strong and not enthusiastic. Other lions, which, along with the lionesses, are provoked* by wild leopards, are neither noble nor brave and have no mane. The honourable lions on the other hand are large and very furry, strong, rapid and fearless. They have a noble heart and know no falseness. They look everything right in the eye and desire of others the same uprightness (?). Their courage (?) can be read in their faces and their tails. The strength of lions resides in their chest and forepaws. In this way, lions are prepared for a challenge at every moment. The lioness gives birth the first time to five cubs. The second birth consists of four cubs, the third three, the fourth two, and the fifth of one cub only. After that, the lioness gives birth to no more cubs. She has no more than two small nipples, in the middle of her abdomen. Augustinus say that the cubs are awoken just three days after birth by the plaintive roaring of their father from a sleep that cannot be distinguished from death.
In the work of Solinus it is stated that a lion does not become rapidly angry, unless someone him causes him pain, but when his anger is awoken, the effect is fatal. He saves, however, those who throw themselves on the ground before him: in this he shows himself to be a lord. Why do soldiers (?) who do not carry the lion in their heart, have him, however, on their shields? If such heroes [the lion?] run up against opposition, they rapidly drive it off, but for the poor (? armies?) and the conquerors (? overcomers?) they know no pardon. If an escaped prisoner, on the other hand, crosses the path of a lion, this will not offend him. People are killed by a lion only when he would otherwise perish of hunger, and then he still preferably kills men – isn’t this noble? – and rather women than untouched virgins.
* ref Babel Fish. Perhaps “confused with” is more logical?
 100 Highlights of the Koninklijke Biblioteek, #6: Der Naturen Bloeme http://www.kb.nl/galerie/100hoogtepunten/006-en.html
 Literatuur Geschiedenis – Nederlandse literatuur van de Middeleeuwen [History of Literature – Dutch literature of the Middle Ages] http://www.literatuurgeschiedenis.nl/teksten.asp?ID=20
 Der Naturen Bloeme [This site has full text as well as wonderfully interactive pictures. However I cannot trace a provenance, such as a library or a museum] http://www.xs4all.nl/~adcs/NatBl/NatBl02b.html#Leo
 L.M.J. Delaissé (1968) A Century of Dutch Manuscript Illumination. Berkeley: University of California Press.
Reference acquired second hand through Aryanhwy.
 Bibliotheek voor de Nederlandse letteren http://www.dbnl.org/tekst/maer002dern01_02/maer002dern01_02_003.htm
 Altavista Babel Fish online translator http://world.altavista.com/tr
 The Medieval Bestiary http://bestiary.ca/