Joel 2:4 Kabbalah

כְּמַרְאֵ֥ה סוּסִ֖ים מַרְאֵ֑הוּ וּכְפָרָשִׁ֖ים כֵּ֥ן יְרוּצֽוּן׃

The appearance of them is as the appearance of horses; And as horsemen, so do they run.

Read kabbalistic (mystical) interpretation of Joel 2:4: and classical mystical sources.