Another translation of Propertius,
by WG Shepherd (Penguin, 1985)
renders the passage below quite
differently:

"I can bring together parted lovers;
I can open your mistress' sluggish doors;
I can physic another's recent wounds-
The medicine in my words is no slight thing.

Cynthia has always taught me what each should seek
And what beware: Love has done *something* for me.
Beware of opposing your mistress when she's cross;
Of lofty speeches; of staying silent long;
If she asks for something, don't refuse and frown;

Don't let kind words descend on you in vain.
When she's contemned, she arrives in a rage.
When hurt, she'll not forget her righteous threats.
The more you're humble, surrendered to love,
The oftener you'll enjoy your good achieved.

The man whose heart shall never be whole and free,
He can continue blest in just one girl."
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Here's Vincent Katz' version:

"I can rejoin separated lovers,
I know how to open a woman's slow doors.
I can cure any recent pain,
not light is the medicine in my words.
Cynthia always taught me which things to pursue
and which to avoid: Love has a certain effect.

Beware of fighting and making her unhappy,
don't boast too much nor be too long silent.
If she has asked for something, don't make a face.
Never let kind words leave her unanswered.
She gets irritated when disrespected,
makes unjust threats in her rage.

The more you are humble, love's subject,
the more you will reap a good harvest.
He will remain happy with one girl
who will never be free, never thoughtless."