That One Verse-4

Original in Sanskrit:

 काम॒स्तदग्रे॒ सम॑वर्त॒ताधि॒ मन॑सो॒ रेत॑: प्रथ॒मं यदासी॑त्
स॒तो बन्धु॒मस॑ति॒ निर॑विन्दन् हृ॒दि प्र॒तीष्या॑ क॒वयो॑ मनी॒षा॥४॥

Joel P. Brereton’s translation:

Then, in the beginning, from thought there developed desire,
which existed as the primal semen.
Searching in their hearts through inspired thinking,
poets found the connection of the existent in the non-existent.

Raimundo Panikkar’s translation[i]:

In the beginning Love arose,
which was the primal germ cell of the mind.
The Seers searching in their hearts with wisdom,
Discovered the connection of Being in Nonbeing.

John Muir’s translation[ii]:

Within it first arose desire,
the primal germ of mind,
Which nothing with existence links,
as sages searching find.

A. L. Basham’s translation[iii]:

In the beginning desire descended on it –
that was the primal seed, born of the mind.
The sages who have searched their hearts with wisdom
know that which is is kin to that which is not.

Max Muller’s translation:

Then first came Love upon it,
the new spring Of mind –
yea, poets in their hearts discerned, Pondering,
this bond between created things And uncreated.

Ralph T.H. Griffith’s translation:

Thereafter rose Desire in the beginning,
Desire, the primal seed and germ of Spirit.
Sages who searched with their heart's thought
discovered the existent's kinship in the non-existent.

Putting It Together:

The subject of this verse is cosmic mind as manifested by desire. Mind is the link between existence and nonexistence.

Desire emerged first. Desire being the seed of the mind, cosmic mind was the first fruit of cosmic sprouting. It is mind that links truth (Sanskrit: sat) with untruth (Sanskrit: asat), being with becoming, changing with unchanging, existence with nonexistence, materiality with immateriality, something with nothing, things created with the uncreated, that which is with that which is not. This is the conclusion of sages and seers with wisdom searching hard with contemplative head and heart (thought and feeling).