READ OUT LOUD. Choose which marked text you prefer to practice with - macrons or accent marks - and read the text out loud until you feel comfortable and confident. Then, try reading the unmarked text at the bottom. It should be easy for you after practicing with the marked texts. :-)
MACRONS. Here is the text with macrons:
Emptum Aethiopem quīdam putābat ita in neglegentiā priōris dominī dēcolōrātum fuisse. Itaque ad sē dēductum, summā cum cūrā lavāre, et dēstringere, et omnī ratiōne annītī, ut sordēs illās, quemadmodum rēbātur, abstergere posset. Vērum mūtāre illum colōrem nōn valuit, Aethiops autem afflictus cūrā in morbum incidit.
ACCENT MARKS. Here is the text with ecclesiastical accents, plus some color-coding for the words of three or more syllables (blue: penultimate stress; red: antepenultimate stress):
Emptum Aethíopem quidam putábat ita in neglegéntia prióris dómini decolorátum fuísse. Ítaque ad se dedúctum, summa cum cura laváre, et destríngere, et omni ratióne anníti, ut sordes illas, quemádmodum rebátur, abstérgere posset. Verum mutáre illum colórem non váluit, Aéthiops autem afflíctus cura in morbum íncidit.
UNMARKED TEXT. Here is the unmarked text - after practicing with the marked text that you prefer, you should not have any trouble with the unmarked text:
Emptum Aethiopem
quidam putabat
ita in neglegentia prioris domini
decoloratum fuisse.
Itaque
ad se deductum,
summa cum cura lavare,
et destringere,
et omni ratione anniti,
ut sordes illas,
quemadmodum rebatur,
abstergere posset.
Verum mutare illum colorem
non valuit,
Aethiops autem
afflictus cura
in morbum incidit.
IMAGE. Here is an illustration for the story (image source) from an edition of the emblems of Alciato:
