READ OUT LOUD. Choose which marked text you prefer to practice with - macrons in verse form, or macrons in prose order, or accent marks in prose order, or focusing on the meter. You will find materials for all of these options below. :-)
VERSE MACRONS. Here is the verse text with macrons (note that the final syllable of anas is long before the caesura):
Altilis allectātor anas, et caerula pennīs,
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Congenerēs cernēns volitāre per āëra turmās,
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Praetēnsa incautās dōnec sub rētia dūcat:
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Perfida cognātō sē sanguine polluit āles,
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PROSE MACRONS. Here is the same text with macrons written out in prose word order:
Anas, altilis allectātor, pennīs caerula, et ad dominōs suōs īre redīre assuēta, cernēns turmās congenerēs per āëra volitāre, garrit et sē recipit in illārum gregem, dōnec incautās dūcat sub rētia praetēnsa: captae obstrepitant; cōnscia at ipsa silet. Āles perfida sanguine cognātō sē polluit, aliīs officiōsa, suīs exitiōsa.
STRESS (ACCENT) MARKS. Here is the prose text with accents, plus some color-coding for the words of three or more syllables (blue: penultimate stress; red: antepenultimate stress):
Anas, áltilis allectátor, pennis caérula, et ad dóminos suos ire redíre assuéta, cernens turmas congéneres per áëra volitáre, garrit et se récipit in illárum gregem, donec incaútas ducat sub rétia praeténsa: captae obstrépitant; cónscia at ipsa silet. Ales pérfida sánguine cognáto se pólluit, áliis officiósa, suis exitiósa.
ELEGIAC COUPLET METER. Below I have used an interpunct dot · to indicate the metrical elements in each line, and a double line || to indicate the hemistichs of the pentameter line.
Altilis· allec·tātor a·nas, et· caerula· pennīs,
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Congene·rēs cer·nēns voli·tāre per· āëra· turmās,
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Praetēn·s~ incau·tās dō·nec sub· rētia· dūcat:
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Perfida· cognā·tō sē· sanguine· polluit· āles,
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IMAGE. Here's an illustration for the fable (image source) from a 1621 edition of the emblems:
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What follows is an unmarked version of the prose rendering to faciliate word searches:
Anas, altilis allectator, pennis caerula, et ad dominos suos ire redire assueta, cernens turmas congeneres per aëra volitare, garrit et se recipit in illarum gregem, donec incautas ducat sub retia praetensa: captae obstrepitant; conscia at ipsa silet. Ales perfida sanguine cognato se polluit, aliis officiosa, suis exitiosa.