Markandeyapurana 47.19

47.19

yasmāttiryakpravṛttiḥ sā tiryakstrotastataḥ smṛtaḥ /
paśvādayaste vikhyātāstamaḥ prāyo hyavedinaḥ //

Because their movement is horizontal, it is called the horizontal stream (tiryak-srotas). / They are well-known as beasts and the like, abounding mostly in darkness and without understanding.

He considered that creation incapable of causation,[9] and thought of creating another yet. While he was meditating on its creation, the animal world, in which the stream of life[10] is horizontal,[11] came next into existence. Since its activities are displayed horizontally, hence it[12] is known as the “tiryak-srotas.” Cattle and other quadrupeds are well-known as being of that kind; they are indeed characterized chiefly by ignorance and are unintelligent; and they stray in wrong courses, and in their ignorance are subservient to knowledge; they are self-swayed, and devoted to self; they comprise twenty-eight classes. They all possess light[6] internally, but they are mutually circumscribed.[13]

47.19.p1

atpathagrāhinaścaiva te 'jñāne jñānamāninaḥ /

Following the wrong path, they think themselves wise in their ignorance,